Prime Slime

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.) When this creature enters, destroy target artifact, enchantment, or land.

As long as this creature is on the battlefield, it has all activated abilities of all creature cards in all graveyards.

{G}: Exile target card from a graveyard. If it was a creature card, put a +1/+1 counter on this creature and you gain 1 life.

As The Mimeoplasm enters, you may exile two creature cards from graveyards. If you do, it enters as a copy of one of those cards with a number of additional +1/+1 counters on it equal to the power of the other card.

Counter target spell, activated ability, or triggered ability. (Mana abilities can't be targeted.)

Whenever a creature you control with deathtouch deals damage to a player or planeswalker, put a +1/+1 counter on that creature. −2: Create a 1/1 black Assassin creature token with deathtouch and "Whenever this token deals damage to a planeswalker, destroy that planeswalker."