Again the regen thing! Wasn't it gone and done?

[Hen-Hen]

If you pull 3 mobs then continue to run to get other 3 mobs I will put a regen after the first pack. If I don't your health will be at mid when you get to the second pack. As a WHM then I will 3x holy which will stun them. Plenty of time for you to get the agro back.
I do agree doing regen before pre pull of first pack is silly. Wait until first "flash" and then do it.

(WHM main)

If I were your tank I'd see that regen and click it off before I reached the second pack, because everything I can't get with my first gcd will come and eat you if I do not, disrupting the pull and screwing up clustering for dps aoe.

If I were playing healer, I'd instead use direct heals to keep the tank going until it was holyspam time, as they generate next to no threat compared to a regen.