Thurva, Essence Curator

Whenever a creature you control dies, put an
appropriate Color counter on Thurva, Essence
Curator for each color in that creature's identity.
(For example, a blue white creature dying would
cause you to put a Blue Color counter and a White
Color counter on Thurva, Essence Curator.)
Remove a Color counter from Thurva, Essence Curator: Add one mana of that color.