The Discord of Melkor

Each player draws a card at the beginning of their
end step.
Whenever an opponent taps a land for mana they
lose 2 life and you gain 2 life. This ability triggers
only once each turn.
Whenever an opponent casts a spell, that player
loses 5 life unless they discard a card.
Melkor spent his spirit in envy and hate, until at last
he could make nothing save in mockery of the thought
of others, and all their works he destroyed if he could.