The only method I can think of is gathering up every assault message I can and using that to enable things that are typically preceeded by an assault, as well as maybe checking on warrior illusions that health has gone down by more than 40, maybe. Any suggestions, hints in the right direction? Barring just enabling the stuff for every class I fight.

Learn lots of Arts and then queue up key system commands like tracking afflictions, cures, defenses, etc. When your Arts training detects an illusion, clear the queue. On the prompt, execute the commands in the queue. More effective than you might think, providing you feel like learning to make artsy things...

Another trick is to put your elixirs in certain types of vials and only trigger on those certain types. If someone illusions that you sip from an emerald vial and the fire elixir warms you (maybe they're trying to freeze you solid), you can laugh at them because you keep your fire elixir in a ruby vial!

Arts I'm not doing, illusion+assault should give a measure of protection. Thanks.

You can try talking to Thoros too. From some of the logs I've seen posted, he has an absurdly good illusion thing he wrote himself. He's also inept arts.