Arrrr! Is It a Potion or a Potions?

Buddy, the ogre is breathing kind of heavily. Bonus action or action, I can't remember. We usually say bonus just for our kill. So he vaguely remembers getting handed a potion in Terry's vault,. He just throws it in his mouth and starts chewing it and swallows it. And if your turn, it's going to use his last legendary action to do ground slam. It brings up all of his tentacles at once, and hits the ground. Everyone within five feet of it has to make strength saving throw.