Rukarumel, Biologist [Commander Masters]

As Rukarumel, Biologist enters the battlefield, choose a creature type.

Slivers yyou control and nontoken creatures you control are the chosen type in addition to their other creature types. The same is true for creature spells you control and creature cards you own that aren't on the battlefield.

3, T: Create a 1/1 colorless Sliver Creature token.