You'll be ok if you just cast a few dots occasionally if the damage to your tank permits it. And you also need to communicate with your tank to recover your MP. Casting attack spells will always be a risk, and it can really drain your MP significantly if you're not careful. So, don't feel pressured to beyond your current comfort zone. If things become unconfortable: plz speak up. It's better than wiping while trying to speed run an instance, ok.