Astéri, World Ender

Costs {x} less to cast, ({x} = # of dinosaurs in play) Whenever a dinosaur leaves the battlefield, create Fossil tokens {s} = to total mana cost
Power and toughness = {s}, ward {s}, vigilance
ETB: Destroy all dinosaurs and then deal {s} to all creatures not under your control.
Extinction {r}{g}{w}: Deal {s} player damage up to 3 opponents and then sacrifice fossil tokens {s} equal
to 1/2 rounded down.