harry potter - What 'spell' inflates Aunt Marge?

Clearly the spell which inflates Aunt Marge in book three isn't a standard spoken spell, and is cast wandless. So there is no real 'spell' to speak of. But what is it most like?

Clearly she expands a considerable amount so it may be similar to engorgio, however she also floats far more easily than she should be able to by sheer buoyancy (She'd need to have inflated to about ~80 cubic meters to get any sort of lift, which is roughly 9 foot in diameter!) so there is some sort of lift element to this charm.

What is the closest spell to the effect she feels when she is inflated?

Answer

There are quite a few spells that could be candidates. I'll bold the ones I think are the most likely to be similar to whatever type of magic occurred to cause Aunt Marge to blow up and float away.

• Anti-gravity mist (incantation unknown) This is a charm which creates an innocent-looking mist which hovers above the ground. A person stepping into this mist immediately finds that up and down have reversed and they are hanging from the ground over the endless sky. Harry encounters this spell in the maze in the Triwizard Tournament. HP Lexicon - Spells


• Banishing Charm (Depulso in Prisoner of Azkaban, the movie; no canon incantation) Sends an object away from the caster; the target object is said to have been Banished. HP Lexicon - Spells


• Cave Inimicum Defensive spell to keep enemies away. HP Lexicon - Spells


• Engorgio Spell that causes a target to swell in size HP Lexicon - Spells



• Evanesco Makes something vanish (not just become invisible, but go away completely) HP Lexicon - Spells


• Feather Light (no incantation given) Spell that makes the target object weigh practically nothing. HP Lexicon - Spells


• Hover Charm (no incantation given) Makes an object float in the air. HP Lexicon - Spells


• Levicorpus Dangles the target person upside-down by the ankle in mid-air. HP Lexicon - Spells


• Mobilicorpus Moves a body HP Lexicon - Spells


• Protean Charm A complex spell that changes the form of something HP Lexicon - Spells


• Repello Spell that keeps something away from the caster or from a target object that the spell is cast upon. HP Lexicon - Spells


• Revulsion Jinx Forces the target to back off from the caster, letting go of him or her if the target is holding on to the caster. HP Lexicon - Spells


• Wingardium Leviosa Causes an object to levitate. HP Lexicon - Spells

I would guess that the closest spells Aunt Marge might have felt like are the Feather Light charm, a hover charm, and Wingardium Leviosa.