Omnath, locus of worlds

landfall — whenever a land enters the battlefield
under your control you may pay {3} if you do
destroy target permanent an opponent controls
that player creates a 1/1 elemental creature token.
u may pay {2} if you do {ut} target permanent.
{t} add {g}{r}{b} to your mana pool.
whenever a permanent leaves the battlefield
you may pay {x} if you do draw {x} cards.