Energy draining vs. interrupts
abomination5
Which do you find more effective for stopping casters? Energy draining might be easier because timing isn't as important. However, I would love learning to do it if it is more effective.
Rhazwyth
Play a mesmer and use both. Interrupt on their longcasting spells like firestorm, then drain otherwise.
MasterDinadan
Arcane Conundrum makes their spells take longer to cast, it will give you more time to interrupt them, but interrupting spells with a cast time of less than 1 second is not possible as far as I can tell... at least, I've never been able to manage it.