Here are examples of teams widely used amongst the Gems of War player community.
Warlock, Valkyrie, Warlock, Warlock
Lantern Banner (Shentang) +2 Yellow, +1 Red, -1 Green
Valkyrie's Spell generates 10 Souls each time it is cast, while the Warlocks' Necromancy Trait increases Souls earnt by 50%. The first Troop in your Team is often the first Troop to be defeated so by having a Warlock in front it protects Valkyrie so she can continue earning Souls even if the first Troop is defeated.
Sunbird, Rowanne, Fire Bomb, Fire Bomb
Abyssal Banner (Blighted Lands) +2 Purple, +1 Red, -1 Yellow
Traitstone farming is done by completing as many Explore Battles as possible as fast as possible so this Team is built for speed on the lowest Explore Difficulty Setting.
Sunbird and Rowanne both do damage split amongst enemies. Fire bomb starts the Battle with full Mana and will defeat an enemy when it casts its Spell, so that means you can defeat 2 opponents at the start of the Battle. When Fire Bomb explodes it also explodes Red Gems to give Sunbird Mana, so you could potentially finish the Battle in 3 or 4 turns.
A similar team variation of this is Sunbird, Bombot, Sunbird, Bombot with Dark Banner.
You could also replace Rowanne or a Fire Bomb with the Weapon Imperial Jewel to earn more Class XP for your Hero at the same time.
Nobend Brothers, Queen Grapplepot, Princess Fizzbang, Goblin King
Dark Elven Banner (Zhul'Kari) +1 Purple, +1 Green
Goblins are great at looping: firstly most Goblin Spells give you an extra turn, secondly, a few of them also explode Gems, which generates Mana for the Team, meaning you can continue casting > gaining an extra turn > casting > gaining an extra turn etc.
In this build the Nobend Brothers take the role of our tank, protecting Queen Grapplepot and Princess Fizzbang in the middle. Queen Grapplepot is the main damage dealer for this Team while Princess Fizzbang can explode a lot of Gems and give the Troops a lot of extra Skill Points. Goblin King is in the last place with high health so if you get into a tricky situation he can summon more Goblins.
The aim is to get Princess Fizzbang looping as much as possible so the Dark Elven Banner is a good choice for this Team, providing +1 Purple and +1 Green gem Bonuses.
When you're ready to cast it's a good idea to cast Spells in this order to increase your chance of looping:
Queen Grapplepot, Nobend Brothers, Princess Fizzbang.
If Nobend Brothers explodes and charges up Grapplepot's AND Fizzbang's Spells, go back to the start and cast Queen Grapplepot's Spell. Cast Princess Fizzbang only when The others' Spells aren't ready, this will maximise your looping potential.
Forest Troll, Nyx, Kraken, Queen Mab
Frozen Banner (Glacial Peaks) +2 Blue, +1 Purple, -1 Red
Forest Troll and Nyx give each other Mana, by creating Gems on the board. You wioll get lucky and sometimes get extra turns from the Gems that are created, making it harder for the other team to take as many turns.
With Queen Mab fully traited, the 4-5 Gem matches Forest Troll and Nyx create will Freeze random enemies, which prevents the enemy from taking an extra turn.
Finally Kraken does a decent amount of damage to the last 2 enemies with the chance to devour the last enemy. In addition, Kraken also creates Blue Gems which will help charge Forest Trolls spell to start the loop with Nyx again.
Although Kraken uses the same Mana colours as Nyx, and Queen Mab is Mana blocked by the first 3 troops as they use Blue and Purple Mana too, a lot of Mana is being generated with this team and there will be enough to power every troop up throughout the match.
Divine Protector, Infernus, Ubastet, Divine Ishbaala
Dragon Banner (Dragon's Claw) +2 Red, +1 Yellow, -1 Brown
This is an advanced Team that a lot of end game players are using at the time this article has been written. It contains a special Event only Weapon (Divine Protector), 2 Mythic Troops (Infernus and Ubastet) and 1 Legendary Troop (Divine Ishbaala).
This is a high damage Team which makes use of a lot of exploding Gems, Storms which generate more Gems of the colours the Team needs and also takes advantage of a Troop Type Team Bonus for Divine Troops. The Hero also heals the Team every turn. Infernus burns all enemies on 4-5 Gem matches AND the entire team starts the battle with 50% Mana.