My current team for Explore difficulty 12 is [6565,1257,6638,6529,3016,2,1,2,3,2,0,0,14014]
Glaycion turns Red to Doomskulls and yellow to blue. Blue goes to Zuul’Goth. Zuul’goth instant kills and creates skulls, which Glaycion attacks with. If he doesn’t match skulls, at least he has 65% skull damage reduction. Leprechaun opens by exploding all green gems and making sure I get 100 gold in battle. That’s important, because the difference between 25 gold in battle and 100 gold in battle is $1396 per fight (using 730% from difficulty, 50% VIP, 100% Armor, and 5% Pet). That’s 6960 for a full kingdom clear!
Doomed Axe creates a Lightstorm which can help refill itself. You remove a lot of the red and yellow gems after you cast Glaycion, so you’re left with a good amount of purple and skulls for Doomed Axe. Every troop has a unique color (Glaycion gets Black and Purple, Doomed Axe gets yellow, Leprechaun gets Green, and Zuul’Goth gets Red and Blue).
It’s a very fast, effective team, I can level up whatever class I want, and I don’t worry about pesky things like immunities 
However… if you want some other fun teams that don’t use Zuul’Goth, try:
- Wrath, Glaycion, Doomed Glaive, King Bloodhammer – doomskull spam, very fast
- Any of the new Guardians – use 3x of them with Hope’s Cresent to one shot enemies
- Obsidius, Essence of Evil, Infernus, Aquaticus – massive splash damage makes quick work of enemies
- Mountain Crusher, The Deep King, The Gray King, Troglodyte – a bit faster I think then the previous splash team, but you need your hero in front line so it’s riskier.