
Originally Posted by
Ferien
IMO, in a situation where you'd be using Atonement (read: near always), saving 300% for Chivalry is silly no matter what, but since you used it as your example, I'll go with it. Normally I'd pop a Chivalry at 100~150 just to give myself some breathing room, and that would free up the rest of the TP for Atonement.
500 MP gives you 5 Cure IVs and 2 Flashes, for ~1800 CE and ~9800 VE. 3 720-damage Atonements give you ~3000 CE and ~9000 VE (assuming a level 85 opponent). In the end it's 400 less total enmity for maybe a few missed attacks (saving some Enmity loss) and some breathing room for your healers. I prefer to handle my curing myself when I can, so the choice is easy.
That being said, it's once every 10 minutes. You can't spare the TP once every 10 minutes? You'll dish out enough Atonements over the course of the fight that skipping out on 1~3 every 10 minutes isn't going to hurt.
Edit: This is obviously ignoring the fact that the damage will shorten the fight. Atonement changed tanking strategy by making the "blow all your MP and pop Chivalry" strategy dumb, but if you're out of MP and need a hit, you'll miss it dearly if it's not up. If everything is absolutely peachy and you never need that MP, then by all means use Atonement instead, because a quicker killspeed will win out 90% of the time.