When you say the Ability it will be given costs random quanta, do you mean any quata type to activate or a random element will be assigned to that ability when it is given?
The abilities won't cost an specific element. It absorbs an random element when you use the ability like when you play a shard.
Umm... Why is it random? Shouldnt it just target the pillar and make that type of priest like Tear does with Nymphs?
Random can render the card useless.
No, you have to use the Cultist of the element when you want a specific ability.
The card only allows every deck to have a chance to use the abilities of other Cultists.