Here are a few ideas i have that people can use, Its up to you to decide what element, cost and whether it is a spell, instant or ability.
InvincibilityProtection from weapon, abilities, creatures, permanents, poison, freezing, the hourglass thingy, etc.
Global all (creatures, permanents, etc.), Specific (power/hp, power/hp < or >), etc.
Specific enemy, you, element, hp/power, hp/power < or >), etc.
Destruction / DamageGlobal non pillar permanents, creatures, weak/strong hp creatures, passive specific (airborne/momentum, etc.)
Specific airborne, power/hp, power/hp < or >, creature specific (dragon, nymph, usually something all elements have), burrowed creature, etc.
HandDiscard you/opponent hand, Global/Opponent Specific (all creatures, permanents, power/hp < or >)
Draw based on you/opponents quantums, based on you/opponents creatures/life/permanents/pillars, etc.
Hand Size decrease/increase
QuantumIncrease/Decrease you/opponent per creature/permanent/opponent quantum, etc.
Colour Change all/stack/single pillar to specific/random pillar, all/you/opponent mark to specific/random, etc.
Casting Cost Costs for Specific/all cards cost less/more (You and/or Opponent)
DeckSearch Specific/(Random from top) and put into hand, discard/(put to bottom) the (top X cards)/specific {pillars,creatures, weapons, etc.) of you/opponent deck.
Refill all/some (random/specific/chosen by owner or user) hand/creatures/permanents back into deck.
Block you and/or opponent cant draw
Oh man, i Have a few others but they are VERY specific....and i am not in the mood to write down all of them (sorry)
But i hope these points will help as well as give people more ideas for new cards.
I mostly based my tips from Magic:The Gathering so i cant take any credit (well I "stole" this from Magic, and wouldnt get any credit anyway from someone whole stole it from me)
But on a final point, dont just think about abilities which help you, maybe you can add a hurtfull ability to a creature with good stats for cheap, etc.
Go crazy ???