Just checked online and saw that you could have done what you wanted and won due to an erratta made in January.
Order of Damage Aplication
In step 6, the attacker chooses the order damage is applied.
(you choose that my monster takes damage first. My monster gets removed from the map first so you win. )
Also, (and I would have told you this if I had realized it) you could have done any time of power attack (with the expection of throw) you could do what you wanted to Ulgoth and not worry about Volatile while your monster was in Hyper form due to Hit & Run on Power Attacks. Body Slam Ulgoth, attacker resolves triggers in any order before Reactions. so you could move three away and not worry about being adjacent.