It's a fantasy role-playing game.

DM: You are Grog Strongjaw, a goliath barbarian . You are the member of the famous group of adventurers. Previously, He uses a healing potion and then starts slashing with his sword at the creature, from the inside. He manages to kill it and gets back up.
DM: Okay, so that's as far as you could get. Because on land it's considered rough terrain. Or, you can go full speed but you'll take damage for every five feet you move full speed. Glass, it sucks. All right, that ends Percy's turn, Grog you're up.
Player: All right, since he killed the big one can I fly down to the one that's right next to Vax with Scanlan on my booty?
DM: Yes you can. (caws) Right next to him.
Player: Yeah. Now, if hopefully I wanted him to lift the form, would I hold my action?
DM: Yes.
Player: Yes! I want to do that.
DM: So holding your attacks until the form is lifted.
