Etnia, Hoofcaller of Selesnya

{t}: Add {g/w}. ({g/w} can be either {g} or {w}.)
Convoke (Your creatures can help cast this spell.
Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
When Etnia, Hoofcaller of Selesnya enters the battlefield, create X 2/2 green Elemental Elk
creature tokens with "When this creature dies,
you gain 2 life."