Changeling Hero

Lifelink is a static ability.

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). See rule 120.3.

If an object changes zones before an effect causes it to deal damage, its last known information is used to determine whether it had lifelink.

The lifelink rules function no matter what zone an object with lifelink deals damage from.

If multiple sources with lifelink deal damage at the same time, they cause separate life gain events (see rules 119.9–10).

Multiple instances of lifelink on the same object are redundant.

Champion represents two triggered abilities. “Champion an [object]” means “When this permanent enters, sacrifice it unless you exile another [object] you control” and “When this permanent leaves the battlefield, return the exiled card to the battlefield under its owner’s control.”

The two abilities represented by champion are linked. See rule 607, “Linked Abilities.”

A permanent is “championed” by another permanent if the latter exiles the former as the direct result of a champion ability.

Changeling is a characteristic-defining ability. “Changeling” means “This object is every creature type.” This ability works everywhere, even outside the game. See rule 604.3.