It depends from the color, the star, and even your own heroes.
From color perspective:
- Red: have DoT, bring for sure green potions
- Blue: defence reducer, overwrite it with a turtle banner
- Green: attack reducer, use a bear banner or pump with mana your buffer
- Yellow: blind, green potions for sure
- Purple: DoT, again green potions
From a star perspective:
1-7* - Titans hits are quite manageable, arrows are somewhat still effective and you can survive quite easy with 4* heroes.
Always have mana potions and you can bring with you arrows and banners.
8*-10* - Titans hits are quite harder, arrow blind occur very rare and 4* heroes start to have some trouble.
Must have mana potions (always) bomb/axe, turtle/dragon banners, big potions or go all out (if you can) with tornado and timestops.
If you take timestops, you can most likely choose to leave at home green potions and heal potions.
Finally, it depends on your own team:
- If you use Boldusk/Kiril, you don’t need banners but most likely mana potions
- If you use Rigard, you don’t need green potions but again mana
- If you use two healers, you most likely don’t need potion at all
- If you use Joon/Justice/Hu tao you don’t need arrows.
- If you use Hell/LittleJohn/Natalya/Merlin you can postpone the special attack and choose to leave at home green potions
Combine all of that to decide what bring in battle.