Current Arcane Flux implementation is very poor, given it's a really small chance (5-15% chance. Read: statistically one in 20-10-6.66 on average) to proc it, not to mention the target you're casting it on needs to stay alive until you finish casting a spell (which can be less successful if in a party with someone high burst damage (gonne, hard critting WM, warlock, etc.) or having summons yourself). One of the following could happen to make it more of a staple mechanic than just spinning the slot machine and hopping for the best:
a) Just drop the chance and change it to "Every X cantrip/hostile GSF casts, get a Flux". Completely spitballing numbers just to give an example but something like "Generalists and Sorcerers get a Flux every 3 casts, specialists every 4 casts, spellswords every 8 hits". Obviously adjusted to what makes sense frequency wise.
b) Keep the chance, but make that after waiting X amount of time out of combat gives a Flux (say, 18-30 seconds so it). Gives something big to open at start (and alleviate the hurt of having very limited spellslots for the duration of full dungeon) and then can chance into even more after
c) Make it possible to accumulate flux like charges. Have two or three charges maximum, and if you get your flux back up but the current fight is mostly over (maybe one or two stragglers left that don't warrant a bigger spell to cast), you can keep cantripping for another flux instead of those casts feeling wasted
