Megatron, Tyrant // Megatron, Destructive Force

More Than Meets the Eye (You may cast this card converted for .)
Your opponents can't cast spells during combat.
At the beginning of your postcombat main phase, you may convert Megatron. If you do, add for each 1 life your opponents have lost this turn.
Living metal (As long as it's 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.