Unearth is a activated ability that appeared on red, black and blue creatures from the Grixis block in shards of Alara block. This activated ability allows you to get an additional use out of creatures that have gone to your graveyard.

Unearth is written as other keyword activated abilities with a cost following the word unearth. This activated ability can only be played when the card with unearth is in your graveyard and only when you can normally play a sorcery. When the unearth ability resolves this creature card is returned to play under your control. It will have haste so you can attack with it that turn or use its activated abilities that have a tap cost (like Vithian Stinger). This ability also generates a delayed triggered ability and a replacement effect. The delayed triggered ability will trigger at the end of the current turn exile the card. The replacement effect does something similar, which is cause this card to be exiled anytime it would leave play and go anywhere other than the exiled zone. This is to prevent a player from returning this card to your hand and repeating / abusing the ability.

Now to a few specific interactions regarding unearth. As mentioned, this is an activated ability and not a spell. This means that a player cannot use effects that counter spells to prevent the unearth ability from resolving.

Also referred to above, the replacement effect generated by unearth causes the card to be exiled if it would leave play and go anywhere else. However, if an effect would exile this unearthed creature, it will ‘succeed’ and exile this card. Normally this does not matter, as the card ends up in the same zone. However if this unearthed creature is removed by something like Journey to Nowhere, it will be returned to play when the Journey to Nowhere’s leaves play trigger resolves. When this creature is returned to play, it is a new creature and it will not be exiled at the end of the current turn and it will go to the graveyard as normal if it is destroyed.