so a 4/4 lifelink trample attacks. My opponent blocks with a 2/2 protection. Would 2 damage be dealt to the player and I would gain 2 lifelink. Correct?
Yes. You assign lethal damage to it then trample the rest to him. Protection would prevent the damage that would be dealt to the creature, in the end is two damage to player, you gain 2 life
Thanks!