text: Activating Cudgel Troll’s ability causes a “regeneration shield” to be created for it. The next time Cudgel Troll would be destroyed that turn, the regeneration shield is used up instead. This works only if Cudgel Troll is dealt lethal damage, dealt damage from a source with deathtouch, or affected by a spell or ability that says to “destroy” it. Other effects that cause Cudgel Troll to be put into the graveyard (such as reducing its toughness to 0 or sacrificing it) don’t destroy it, so regeneration won’t save it. If it hasn’t been used, the regeneration shield goes away as the turn ends.