Quote Originally Posted by Deceptus View Post
My anecdotal evidence proves otherwise.

In the half second (seems longer TBH) after you cast Regen if the tank aggros the mobs, they WILL go after me the healer.

Have had regen on the tank saw them charge in, and still got aggro before. There's something funky with the system (like all systems in FFXIV).
Applying a buff generates a tiny amount of enmity (was equal to player level back at ARR, HW, SB, iirc). Let's say the 90 enmity. Face-pulling grants only 1 Enmity. As such, you pull off the tank with your ~89 extra enmity.

If HoT ticks themselves cause no Enmity, then the tank popping a defensive, even, will pull those back even if your HoT has ticked once already. I've had Regen pull off me often, in which case I just pop my least valuable defensive a little earlier to regain aggro enough to Flood them as I keep running. Even with a tick registered in combat, the self-buff seems enough, so no idea yet from experience whether HoTs produce no Enmity per tick or just miniscule amounts.