Teal for the most part on most non high int mobs. I did some numbers for puddings since they happen to have a high reasonable amount of int(89, no latents/day/weather you should do a thunder IV for around 1580 to them) and teal came in even with morri with your current gear. I assumed full int merits and creampuffs aswell with that. I didnt account for your Mcrit rate as I dont think it will change the outcome. Teal is definately the way to go for tierV if you cast those aswell.
I would assume your best bet would be to use teal on most non resistant mobs and use morri on any HNM type of mob(although probably minimal difference on either end). Though as a taru, you probably can still get away with teal on HNMs with your natural high int and lucky weskit.
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