It's been long since I last used my R Diablo, and I'd want him to deal good amount of damage next time I play him (in a Classic FF Foes team)... Basically, I want to keep pushing him using Toxic Burst, then land on his Regen clicks, then have a good Regen roll, then TB again, etc... (and maybe a few shots between, with lucky rolls; I know it's a lot of points for a puny fig but I want him to be annoying, that's all...).
Question is: at the beginning of my turn, R Diablo is on his first click of Regen: he uses Auto-Regen, and rolls a 5, which drives him on his last click of Poison: can he use Poison then (or Toxic Burst)?
I'd say yes, because Poison (or Toxic Burst) and Auto-Regen are both supposed to take place at the beginning of my turn, and are both free actions; am I right?

You are right. You cannot do this with normal Regeneration though as that takes place after the beginning of the turn.

Thanks Quebbster. I knew it wouldn't work with Regen alone (since you'd have to take a non-free action to use Regen, so you wouldn't be "at the beginning of your turn" after that), but I wasn't so sure about Auto-Regen.

Anything that has to take place at the beginning of your turn such as auto-regen, poison, leadership. It is the players choice on which events occur in which order...

I knew that too, thanks burnout1445 (it's like Outwiting a damage-reducing power before dealing Poison's damage ), it's just that I needed to have a "written" proof before using it against a friend (and yes I know HCR's rulings aren't supposed to be official because blah blah blah..., but I don't care and they're official to me ).

Page 16 of the Danger Room rulebook.