You see, regenerate is another word for: “The next time this creature would be destroyed during this turn, tap it, remove it from combat, and remove all damage from it instead.” That means anytime after the shield is created, as long as it’s within the same turn.
Usually when you “regenerate” a creature, it’s right before its impending destruction. In this case, however, there is no impending doom in sight for your creature. It obtains a regeneration “shield” before the Trollhide is destroyed, and the regeneration effect is linked to the creature, not to the enchantment. So even if your opponent goes on to block and try to kill the creature after getting rid of Trollhide, that regeneration shield you created will still kick in. Nice play!
Today’s Rules Tip written by Eddie Cheung