A few card suggestions

[Beo]

How about a "co-opt" or "turn enemy" card that allows you to take one of the opponent's cards from their field and bring over to your own.

Similarly, how about a power drain spell that can temporarily eliminate or reduce the quantums generated by a pillar stack, or maybe can draw those quantums over to your side during the operation of the spell.

How about a mortality spell that removes immortality for 1 to 3 turns.

Not a only card suggestion, but what about different kinds of damage, like heat, cold, electricity, acid, etc:  Certain elements would be immune (fire is immune to heat, water to cold, etc.) but additional cards could grant creatures or the player permanent/temporary immunities.  Is this too complex to track / play?  I suppose it's a fairly major revision of gameplay.

[ajm6]

The co-opt spell you are talking about seems very similar to parallel universe and if the only difference from PU is that it removes the card from the opponent's field it won't make it into the game as that is an instant kill card.

For the reduction of enemy quanta you may want to look at the black hole and devourer cards both of which reduce the opponents quanta and have other benefits though they don't act on pillars.

As for the mortality spell aether has already been nerfed so I don't think a mortality spell is likely to come any time soon. Not bad ideas but alternate methods to achieve the same effect already exist.

For the damage types its not a bad idea and might happen some day, but it is a major game revision so I don't see it happening soon.

[assassim]

The turn creature card has been suggested many times before and many disaprove of this as it combines PU and destroys their creature all in one card.

[rex87]

I also thought about this

a spy is needed to bring them over

or quantums have to be paid to the opponent

[bobcamel]

Been there as well, and stated such a card would have to have a temporary effect, not turn permanently, then it'd be fine.