If you have a weapon with a chance on hit for a bleed, and your signature spell triggers it, each bleed tick will count towards your arcane dynamo stacks, allowing you to spam a spell like arcane orb multiple times at 5 stacks.
I have managed to get 4 casts off before having to get another bleed up as the bleed ticks REALLY fast, where you get to 5 stacks in less then a second after casting a non-signature spell.
1. Get chance on hit for bleed
2. Trigger bleed with a signature spell like magic missile
3. spam non-signature spell while stacks constantly rise to 5.