Otharia Tekoa, Titan of Beasts

Trample, reach
As long as Otharia Tekoa is in play, land you
control and cast can only be used to cast cards
with power 4 or greater. You also get an emblem
until Otharia Tekoa dies with "Creatures you
cast with power and toughness 6 or greater cost
mana equal to half that creature's converted
mana cost.
It's Strong enough to annihilate planets.