Is regeneration a spell in magic the gathering?

Answer 1

'Regenerate' is an ability that allows a permanent to survive a destruction effect, or lethal damage.

Activating the Regenerate ability will give the permanent what is known as a 'regeneration shield' for the rest of the turn. If the permanent is affected by something that tries to Destroy it, or it is dealt lethal damage, then the shield is removed and the permanent remains in play. All damage is removed, and the permanent is tapped. It is also removed from combat, so will not deal combat damage although if it was used to block, the attacker still counts as being blocked.

The Regeneration ability does not have to be used directly in response to the destruction effect itself, though it is perfectly legal to use it at that time. Multiple regeneration shields can be active at any one time. So if you had a permanent that can regenerate other permanents, and the opponent targeted it with a card to remove it from play, you could activate its effect to distribute regeneration shields onto your other permanents in response, which will shield them throughout the turn even though the regenerator itself is gone.

Sacrificing a permanent does not 'destroy' it, so Regeneration does nothing against that. Regeneration does not resurrect a dead card (so can not bring things back from the graveyard) it merely prevents destruction. Some destroy and damage effects prevent regeneration. 'Bury' is an obsolete term, but means 'destroy without allowing regeneration'.

Answer 2

Regeneration is an ability, but there is also a spell of the same name, an Aura that lets the enchanted creature regenerate.