KISS theory, Keep It Simple Stupid, don't add uneccisary complexity, adding lots of simple things makes a complex world on its own you could have it be something like
Tribbilion Ooze - cost 4 - rare -
Clanless - ooze
requirement - 2 any clan
attack 1, hp 3, move 2, vision 1, atk range 0
pay 2: put a copy of this into an adjacent space.
No corpse, when killed is immediatly removed from the battlefield
creature spawning more of themselves is always awsome, although it is a Viral ability (because thats exactly how viruses work) i think the ability should at least not be available at one clan rank, and having them be difficutl to destroy is going to be a nightmare, especialy if they stay when there destroyed like most creatures, you'd be able to make an unpassable wall, especialy in narrow passes far to easily. As for other abilities, you could have other creatures that have ways to use oozes and those abilities not be intrinsic to the ooze, each clan could have one, i would make the ooze as common or moreso then the creatures that use them, otherwise people are going to be sitting around with all these cool cards and be like, is there even an ooze in the game?
Oh and my name for it is a combination between tribble and billion, i though it was a cute name for it.
Other options whould be it spans another copy anytime it is attacked but not killed, or when it dies put two in play with half the total HP the origanal did, and have this chain down the line, each time reducing the scale of HP and possably power if its higher then one. Cool concept though, there are not enough oozes in many a world, i believe they were annihalted in the conquest of the jellos.