Tom, Irascible Electromancer

Whenever Tom, Irascible Electromancer
enters the battlefield, choose artifact,
creature or instant.
Whenever an opponent casts a spell of the
chosen type, deal 3 damage to any target,
look at the top of your library and put into your graveyard.
Whenever you discard a card or a card is
put into your graveyard, draw a card.
If your life total is below 15,
draw 2 cards instead.