Which DOT are worth the cast?
I'm actually hesitant to cast most DOT spells because the time it takes to cast them are usually best spent casting other spells.
From some testing, I saw that Thunder 1 was about equivalent to 1 cast of Fire 1.
The potency and length of time of each type of DOT spell varies from eachother.
Is it worth using a cross class ability slot to fill them in with DOT spells?
Other than utility, like Aero's instant cast to mark targets for classes that don't have a range attack yet,
I'm not sure which spells are effective.
The new class ACN's main way of dealing damage is through DOT spells as well.
I do know that it's not a good idea to cast DOT spells on targets that die too fast before the spell runs it's course such as in FATES.