start of build idea

goal - disable casters

mesmer

12+4 fast casting
10+1 domination
8+1 illusion

1. echo - copies next skill cast for 20 seconds
2. blackout - taget foe cant use skills for 6 seconds, you cant use skills for 5 seconds

cast echo then cast backfire and you could cast another backfire using echo after 5 seconds and then cast another after that because the real backfire would be recharged and then after that cast the backfire from echo again, making the target backfired for just over 20 seconds, and then start all over with the process or cast other skills

would this work to make sure for example a monk couldnt cast any heals or other spells

edit - wrong spell listed there lol, edited to say blackout

Backfire - 15e 3c 20re (domination) for 10 seconds whenever target foe casts a spell that foe takes 35-119 damage.

first...backfire itself will last for 10 seconds on target (the overall damage is the modifier, not the time).. if you try casting backfire on itself from any source..it will just reset..can't stack them. You could however cast echo...then backfire on target...then cast echoed backfire on different target..then 2 would be under backfire in that short time allotment.

a decent combo to add in the mix is IW

while your skills are disabled, you can attack with this one as long as you had it up before you casted blackout.