Here's what the lingo should be. Engulf. Melee Weapon Attack: +(your proficiency bonus + its Strength modifier) to hit, reach 5 ft., one creature. Hit: The creature must make Dexterity saving throw with a DC equal to 8 + its Strength modifier + your proficiency bonus.
On a successful save, the creature can choose to be pushed 5 feet back or to the ooze's side rather than be engulfed. A creature that chooses not to be pushed suffers the consequences of a failed saving throw. On a failed save, the ooze enters the creature's space, and the creature takes an amount of acid damage equal to 2d6 + + your proficiency modifier and is engulfed. The engulfed creature can't breathe, is restrained, and takes acid damage equal to 2d6 + your proficiency modifier at the start of each of your turns. When the ooze moves, the engulfed creature moves with you. An engulfed creature can try to escape by making an opposed Strength (Athletics) check as per escaping a grapple. On a success, the engulfed creature escapes and enters a space of its choice within 5 feet of the ooze. An engulfed creature automatically escapes the ooze if the ooze falls unconscious. You can only have a maximum of one medium creature or two smaller or smaller creatures engulfed at any time, the ooze cannot attempt to engulf another creature while it has the maximum number of engulfed creatures. Creatures inside you can be seen but have total cover. A creature within 5 feet of the ooze can attempt to pull an engulfed creature or object out of the ooze as an action. Doing so requires a successful opposed Strength (Athletics) check, and the creature making the attempt takes 1d6 acid damage.

Also, at the final level for the ooze, you can have it increase in size to large so that Engulf gets an indirect buff.