I don't think Ursa's ability was broken imo but it was allowed to be exploited because the fireworks that stun the beast had zero cool down and no limit on how many you could purchase (as long as you had enough ingnots)
Without being able to perma stun the beast, Ursa's stacks would reset because he would either get stunned by the beast or he would have to kite some of the magic abilities from time to time.
Without being able to perma stun the beast, Ursa's stacks would reset because he would either get stunned by the beast or he would have to kite some of the magic abilities from time to time.

Even if he has said "never say never", like you say... why give up the BTS gig, who offer him a decent place to live (as far as I'm aware they do anyway..?) and what is probably a decent enough salary as well, to keep doing what you love.