The philosophy of team building
Teambuilding basics
Connon Strategies
Counters to common strategie
Guild / Event Team Ideas
Team building philosophy
In my mind, there is no "best team", only the best team for the situation you are in that happens to use what you have at hand. There are players who say you can't win unless you use a specific combo with a ton of ultra rare stuff. That's false. You just need to be creative and patient, then you will win. Always look at your opponents, then build your team to counter their strategy. It may take several tries to find a winning solution, but there always is one if you keep looking and thinking.This outlook makes me unusual, but my unusual teambuilding approach has let me be in the top 20% every single time there is a guild event, so there just may be merit in being unconventional! If you are wondering, the top percentages are mostly made of people who play this game for 6+ hours a day and spend lots of real money on it. Breaking the top 20% when you never buy anything and only play for an hour or two a day is really, really good.
When you are getting started, remember that you are new. Work with what you have as best as you can. Do not stress over not having the most popular rare things out there. Just be the best you can, and you will get somewhere. I hope these ideas help you along the long journey to somewhere.
Teambuilding Basics
At it's core, you ideally want a team that uses every color so you can build up faster. When everything uses the same colors, the troop on top will have it's mana fill first. Once it's full, the one below it will start to fill. This can really slow you down! Expensive troops should not be on top, either, as they will take forever to fill up. Nothing with that expensive troop's colors will be able to start to fill until the expensive troop is full. This can result in getting killed before you can do anything. Also, when everything uses the same color, freeze becomes a major problem: one frozen troop stalls the entire team. Using multiple colors reduces freeze danger as you can always focus on another color for a little while.Multi-color troops are helpful as they can fill up with more than one color. This way, you can have two troops with the same color but both of them can fill up at the same time! Also, any extra left over from building the troop on top will trickle down to help fill up troops of the same color below it. The drawback with multi-color troops is that if they are frozen, all colors they have will be affected. The only time this isn't the case is when a troop uses all colors. I'm not sure if it's a glitch, but the game doesn't seem to count that as frozen at all. If you see a troop that uses all colors, kill it first, especially if it's a hero. That troop is going to be a thorn in your side until it goes down. But, once it does, expect the fight to get a lot easier.
Also, pay attention to attack, health, and mana costs. Attack is used when you match skulls. If you want to use skulls, pick troops with higher attack. Beware of charm, though, as high attack makes it a lot more dangerous. If you want to use a lot of spells, look carefully at what the spell costs versus it's mana cost. Can you get that cost paid in a reasonable number of turns? Is the effect worth the cost? If the answer is no, pick something else or get some support going so you can make things better. Finally, health is crucial to all troops. It doesn't matter how hard they can hit if they die before they can do anything. Low health troops need lots of defense or support to back them up or they are unplayable, IMHO.
Choose your hero class and weapon to compliment your team. Don't build around a hero in general. There's four team mates and one hero, so make those four count!
Common Team Setups
These are some of the most common teams you see in the game. I will note ones that are especially popular in PvP by marking them (PvP) but bear in mind that these teams can appear anywhere. PvP is just one option. Things marked (risky) will work, but you need to be careful about it!
Glass Cannon (PvP)
Team has 2 or more low health troops that attack quickly and deal a lot of damage. This team does not defend at all. Any support troops actually generate mana so the attackers can move faster and/or take extra turns. The support is probably actully the hero and the hero is going to have a class that uses freeze to try to slow you down. Looping troops are very common as the attackers in this team. This is usually the most popular team type in PvP.
Countered by: Nerfer, Monkey Wrench, Dodger, Armored Cannon (risky), Vampire (risky), Bruiser (risky)
Best against: Enemies smaller than you, Glass Cannon, Armored Cannon
Armored Cannon
What happens when you slow the glass cannon down a little, but add in some shields and health so your attackers don't die so fast? You get this team! Scatter damage, full team damage, and looping troops will make up the heart of the team. The support creates shields, blesses, and/or adds health to keep the cannons happy. This is roughly the second most common team type in PvP.
Countered by: Nerfer, Monkey Wrench, Dodger
Best against: Enemies smaller than you, Glass Cannon, Summoner, Wall
Booster (PvP)
This team is always boosting it's stats. Most commonnly in PvP, you see this as a glass cannon hybrid where arcane is used with a looper to make something one hit kill out of sheer damage. Sometimes you see skull damage teams use Grudge, but it's the less common option. Urska and orcs tend to use this tactic.
Countered by: Monkey Wrench, Vampire, Nerfer
Best against: Glass Cannon, Armored Cannon, Wall
Nerfer (PvP)
This team focuses on weakening the opponent. Let them spam attacks; those attacks won't do enough damage to matter! Nerfers use magic drain and attack drain to make an enemy very weak. Then they go in for the kill. Usually this is a defensive setup to assure that the draining troops can do their job before being killed. It's a slow win, but shockingly effective. Dark elves (Zuul'Kari) tend to use this tactic.
Countered by: Booster, Summoner, Cleric, Wall
Best against: Armored Cannon, Glass Cannon
Vampire
A Nerfer variant that uses life drain, magic drain, and/or attack drain to boost your team. Typically this requires careful support as most draining troops are either slow or don't drain very much at once. With good support, however, these are extremely durable teams. Pack at least one mana generator, stat booster, and/or shielder to help protect your team. Literal vampires and unddead troops tend to use this tactic.
Countered by: Monkey Wrench, Booster, Nerfer, Cleric
Best against: Wall, Dodger
Monkey Wrrench
A team built just to give common teams a hard time. They don't worry so much about dealing damage as prevening opponents from using abilities, spells, and extra turns. The theory is that if the opponent can't do anything, then you are going to win. Expect to see silence, stun, freeze, shield, submerge, and other defensive support moves. Usually a monkey wrench targets sepll damage (magic) more than skulls (attack). Sometimes seen in Leonis Empire, Merfolk, daemons, or giants.
Countered by: Bruiser, Wall, Cleric, Wall, Bruiser
Best against: Glass Cannon, Armored Cannon, Booster
Dodger
A monkey wrench variant that tries to avoid whatever damaging move the opponent is using. Are they using scatter damage? Use submerge! Are they using instant kill? Use invulnerable or stealth! These teams are always very situation specific. You don't see these defending in PvP, but you will probably end up using one at some point as an attacker. Merfolk and dryads tend to use this tactic.
Countered by: Monkey Wrench, Vampire, Nerfer, Bruiser (if your team avoids magic)
Best against: Glass Cannon, Armored Cannon, Booster, Bruiser (if your team avoids skulls)
Wall
This team has massive defenses. The goal is to gain armor, shields, and/or health every single turn, even when you aren't using any spells. Spells only make you gain even MORE. This team tries to outlast the enemy, hoping they make mistakes. There usually is just one really good attacker or one summoner who waits until the first troop (usually a literal wall) has fallen, then starts to summon things to attack on behalf of the team. Knights use this tactic a lot.
Countered by: Glass Cannon, Armored Cannon, Vampire
Best against: Dodger, booster, Bruiser
Cleric
A slightly more offense driven wall variant here about half of the team boosts health and removes negative statuses. The other half is made up of things that attack quickly, especially if they loop. The idea is making a wall that can actually hurt the opponent. Centaurs and Whitehelm tend to use this tactic.
Countered by: Glass cannon, Dodger
Best against: Monkey Wrench, Wall, Summoner
Summoner
Your base team is not the real team. It's actually a support system that lets your boost and protect your summoner. Your troops are not so strong, but there are so many of them that your opponent can't kill them all. Stealth or health gain is used to protect the summoner so the team can keep on fighting. Goblins, Dark Elves, daemons, and Kobolds use this tactic.
Countered by: Scatter damage, Glass Cannon, Armored cannon, Monkey Wrench
Best against: Vampire, Wall, Cleric, Dodger, One Hit Kill
One Hit Kill (PvP)
A team centered on one or two very expensive troops that kill things in a single hit. The hero (if there is one) is probably a Thief so they can use Assaninate. Other troops are either glass cannons there to distract you or mana generating support, especially ones that use explosions or looping for more mana. The one hit killer troop usually is invulnerable, but it's support team is not. Kill the support to cripple this team. This is the team type seen in Boss fights during guild events.
Countered by: Monkey Wrench, Summoner (risky), Nerfer, Dodger
Best against: Wall, Glass Cannon, Cleric, Booster (risky)
Bruiser
Who needs magic when you can just punch things to death? This team spams skulls. Everything should either resist or dodge skull damage. Magic resistance and/or shield are useful additions. Boosting your attack with grudge is always a nice touch. Mydnite, Khetar, and various undead troops use this tactic.
Countered by: Monkey Wrench, Summoner (risky), Nerfer
Best against: Wall, Glass Cannon (risky), Cleric, Booster (risky)
Guild / Event Team Ideas
Once you have joined a guild, you will see a different event every week. There also are seasonal events that appear every few months, running for two weeks each. The actual troops you will get to use will vary, but the strategy behind the opposing team won't change very much. Plan against the team type and you'll be fine.
Tower of Doom
A bunch of random themed rooms will lead up to the main event: a boss fight against a "Doom". Dooms are always invulnerable, but their team is not. You can choose to nerf or instant kill the Doom's support, then focus on the Doom. Alternatively, bless your team every time the Doom attacks. This will remove the death mark the Doom creates keeping your team safe. There are always weapons in the shop that deal more damage to dooms, but unless the effect of the weapon can be boosted, it won't do much on higher levels. It's best not to focus too much on that anti-doom weapon because of it. Speaking of that weapon, try not to use the weapon's color as your primary team color. The enemy teams are always built to counter whatever color the anti-doom weapon is!
Invasion
Your opponent will have towers. Eventually all opponents will be towers! Pick troops that deal extra damage to Towers. One anti-tower troop will be availiable in the guild shop, but you may have more unlocked already so use those, too, if you have them. Towers are invulnerable, so don't bother with instant kill or statuses like silence. Just deal as much damage as you can as fast as you can. Kill any Arcane towers first so they can't drain your magic. Also consider packing some anti-status and/or health gain to help against towers that deal true damage or light your team on fire.
Boss Raid
Your opponent will be one Boss with an instant-kill move and a suppotring team. The supporting team usually generates mana, but sometimes they can heal or deal lots of damage. Always focus on killing the boss first! Use any and all anti-boss troops you can. Choose a hero with "Stealthy" as one of their abilities (Thief or NightCaller are examples) and give them a weapon that summons troops. Use this to call for backup just in case someone dies.
Journey
You will be fighting random teams that escalate in difficulty very fast. You are expected to buy the looping troop from the guild shop in order to deal as much damage as possible. Pack troops that create mana your looping troop can use or other looping troops that use the same mana (if you have them). Also consider packing troops with Arcane so they can attack very hard if your looper fails. A stealthy hero with a wepaon that summons things makes for very good backup. Alternatively, a hero that generates a lot of mana with a high level summonner troop is nice. Always check the opponent before you fight them. Some opposing teams are more trouble than they are worth. If it takes you two tries to defeat one enemy, you are making less progress than if you went for the easier option. When in doubt, take the easier option.
Seasonal Event
There will be five different enemy teams, all themed to the season. Your team will be forced to match. For example, Springtime typically has forest creatues, flowers, and faeries. Your team will be restricted to the color green. You will get three tries per day for free. These tries do not stack up, so make sure you play every single day in order to get the best results.
You can switch teams here as long as they fit whatever restrictions the season is using. If your current team doesn't look good, change it up! You can also just choose to fight the same enemy team over and over. It won't change much, even if you go up in difficulty. This prevents surprises.