Megatron, Tyrant

three generic mana one red mana one white mana one black mana Legendary Artifact Creature — Robot·7/5

More Than Meets the Eye one generic mana

(You may cast this card converted for one generic mana

.)
Your opponents can't cast spells during combat.
At the beginning of each of your postcombat main phases, you may convert Megatron. If you do, add one colorless mana

for each 1 life your opponents have lost this turn.

Megatron, Destructive Force

Legendary Artifact — Vehicle·4/5

Living metal (During your turn, this Vehicle is also a creature.)
Whenever Megatron attacks, you may sacrifice another artifact. When you do, Megatron deals damage equal to the sacrificed artifact's mana value to target creature. If excess damage would be dealt to that creature this way, instead that damage is dealt to that creature's controller and you convert Megatron.