Do you mean like:
Plague:When attacking, suffer –2 Attack. If you hit, opponent takes no Damage now, but takes 1 Damage at the start of each of their turns for 3 turns, or until healed. The opponent may skip each turn to avoid taking this Damage. Fleeing is not skipping a turn.
Some of the opponents have similar, but less permanent effects. Poisonous Spiders and Brain Eating Zombies.
something like this.
you can put a plague on a creature.
it could weaken the defense/ and or attacks.
it could cripple it's special effects, like "no flying anymore"
this creature can give thi splague onto other creatures.too.
with in incubation period of x-times turns. yo could kill th ecreature to prevent it. or cast some special healer card.... ->just an example ofcours.
thi scould be fun. you give your opponent a plague. and you have a spell that exchange your creature to a creature of your opponent. now the the other player has this plague!
