Does a creature with Lifelink provide lifegain equal to its power, or the defender's toughness?

Question

I have recently began playing a deck that has a number of creatures with lifelink in it. I want to be certain I understand the mechanic and the following question occurred to me.

Which damage total do you use to determine the life gain from lifelink? I had assumed that if a 3/3 creature with lifelink was blocked by a 2/2 creature that the life gain total would be 2, the maximum that the blocker can absorb before dying. This seems to be incorrect, as when I read the example attached to CR 119.4c

[...] attacks with a 3/3 creature with wither and lifelink. It’s blocked by a 2/2 creature, [...]. The damage event starts out as [3 damage is dealt to the 2/2 creature, 2 damage is dealt to the 3/3 creature]

Have I been short changing myself?

Answer 1

Yes, you've been shortchanging yourself!

702.14b Damage dealt by a source with lifelink causes that source's controller, or its owner if it has no controller, to gain that much life (in addition to any other results that damage causes).

A creature with 10 power blocked by a creature with 1 toughness deals 10 damage to that poor little blocker. Creatures with 10 power are not known for their discretion or moderation; they don't deal 1 damage on the grounds that that will be enough to do the job. No, they smash that blocker into smithereens and leave behind a smoking crater!

I think your confusion may arise from the old card Drain Life, whose text reads:

Drain Life deals X damage to target creature or player. You gain life equal to the damage dealt, but not more life than the player's life total before Drain Life dealt damage or the creature's toughness.

Drain Life is the exception though, not the rule; for lifelinkers the creature's toughness is irrelevant in determining how much life is gained. (See also though Abattoir Ghoul, a recent card which offers a kind of new spin on the Drain Life idea.)

Answer 2

Yes, you have. When a creature with lifelink does damage, you gain life equal to that creature's power, since that is how much damage it deals (outside of a few corner cases).

In the case of a 3/3 lifelink creature being blocked by a 2/2 creature, the 3/3 creature still does 3 damage to the blocking creature, even though 2 damage would be sufficient to kill it. Therefore you gain 3 life.

(The cases where this does not happen include cases where damage is prevented, such as if your opponent plays Fog, or if the blocking creature has protection from your creature's color.)

Answer 3

I had assumed that if a 3/3 creature with lifelink was blocked by a 2/2 creature that the life gain total would be 2, the maximum that the blocker can absorb before dying.

This is somewhat incorrect. Creatures don't "absorb" damage. Strictly speaking, dealing damage and killing a creature are separate game events. Damage is marked on creatures, and every time state based actions are checked, the damage marked on every non-indestructible creature is compared to its toughness, and every time the former is greater than or equal to the latter, the creature in question dies. This is why, for instance, Sengir Vampire says "Whenever a creature dealt damage by Sengir Vampire this turn dies" rather than "Whenever a creature is killed by Sengir Vampire". Sengir Vampire doesn't actually kill creatures: it deals damage to them, and then the damage kills them.

When a creature you control with lifelink deals damage, the sequence of events is: damage is dealt, then you gain life, then the damage dealt is compared to the toughness of the creature that was dealt damage. The toughness of the creature is irrelevant to life gain, and isn't checked until after the life gain. The life gain is the damage dealt. The other creature is indestructible? The life gain is still the damage dealt. The creature dealing damage has deathtouch? The life gain is the damage dealt.