First off: This hack was found by Super/FM69, and he said to release this, so please accept the thread mods.
Here's how you do it:
Get a party - 1 person is a hermit/CB or NL/Shadower, other person can be anyone.
Summon dark flare, get hit by the monster you want to attack
Record getting hit packet (header 34 00)
Change the damage value in the packet from whatever, to 0f 0f 0f 0f, and send it. It should do about 21M dmg to the monster. Dark flare only does 50% of a monsters max HP so on low HP monsters it may not do 21m, it will do 50% instead.
And then you will die. Use revive hack, and resend the damage packet to hit the monster again, and so on. If you are a fast reviver, you can do very fast damage.
Some values will even heal monsters, I assume this is because of integer overflow and the fact that this skill most likely uses its own formula.
anyways enjoy, and keep the hacks public.
ALL CREDITS TO SUPER/FM69, this has been his hack for a long time.