[JASS] Need help with a spell - electric discharge

Level 12
Nov 5, 2007
I need a script for the following 3-leveled spell.

When cast, it's supposed to affect all units within a 450 AoE radius, deal damage equal to 40, 50 and 60% of the casters current mana, and drain an equal amount of mana from the caster. It should also knock afflicted targets back for 100/200/300 range, please note that the knockback should destroy destructibles and it should have a straight line (away from the caster, I've seen a bunch of similar spells that just send the unit flying in random angles). The AoE animation should be a basic thunder clap, and knockbacked units should have something like purge on them (while they're flying).

Help will be greatly appreciated.