Well... You see, a card can only have ONE ability, no matter if the ability is active or passive. Devourer is the only exception. I think Zanz personally said that.
Scarabs have two. From reading the forums, most people say that a creature can have 1 passive and 1 active ability.
Devourer - Absorb and Burrow, one active, one passive
Scarabs - Devour and Swarm, one active, one passive
Sundial - Hasten and Stasis, one active, one passive
Graboid - (enters the game) Burrowed and Evolve, one active, one passive
That is not to mention the status cards you can apply to a creature - which do
not over-ride the creatures active abilitiy...
Otyugh with Momentum can still Devour
Fallen Elf with Immortality can still Mutate
Firefly Queen with Adrenaline can still Spawn Firefly
And on top of this, creatures
can have two, or more passive abilities.
Firefly has luminescence and can have Adrenaline and Momentum for example.
So, there is nothing to stop a Malignant cell from having two.
Malignant Cell - Merge and Duplicate, one active... and... one passive.
1. You forgot the images
2. It is meant to fill up the board. Usually the enemy's, so yes, SO HE CAN'T PLAY ANYTHING. It's perfectly fine as it is.
1. I'll add the images later today.
2. Does my suggested re-working of the card mean that it does not fill up the opponents board?
No. It simply means that if your opponent wanted to, he could spend
to get rid of
one Malignant Cell. Sure, it might defeat the purpose of filling your opponents side of the board with Cells - but I've still not seen any evidence that people are actively using this tactic as a successful way of winning in PvP encounters.