The 3rd stage of the annual John Van Caneghem Tournament (2007).

Whose mana is infinite? For example, djinns cast different spells without any mana:D

They cast spells without mana, but only 3 times per battle.
And this isn't magic, but their ability, just like with the tent – it's all an ability. Trolls also regenerate not with magic, but with an ability.