I got as far as Purify (exactly the effect you suggested) and Deflagration (destroys an improvement), after which I discarded the whole idea as "too complex".
I'm not done reading all the stuff in the WoE section, so I'm not quite into it, yet. But to throw a couple of ideas around that might inspire someone:
All spells are discarded after use, except gravity which discard another card.

Paralell Universe Quintessence -> Invisible for x turns.

Unstable Gas -> In the next NPC fight, that NPC has 20 less maxhealth (does not stack, opponent just surrenders when hp are below 20)

Steal -> Steal a card from target.

Poison. -> One is sick for x turns. (can't take any actions)

Graboid -> Spawns a NPC that attacks opponents entering that field. (there until defeated)

Chaos Seed -> Does NOT cause cure

Rage Poiton -> Free Attack. Or a follow attack costs less action points.

Cat-A-Pult. -> throws around schrödinger cats.

Adrenaline -> 1 additional movement.

Miracle -> Used before battle. If you lose, you get a rematch and the previous isn't counted. (probably something else is better than a rare card)

Either Precognition -> Get information on something you usually don't get. Or: Golden Hourglass -> One additional action point. (discard 2 time Pillars when used)

Purify -> Cures negative effects.

Dagger -> Target opponent starts with 10 less health (surrenders when hp goes below 10)