[Balthis]

In l2script the chance to drain hp is 100%
For example you hit 100 times and you drain 100% of the times.

In l2off the chance to drain is 50%, there is no OFFICIAL info about this. I did some test like hitting a 100 of times.

You know when you drain because the green message (HP Heal) appears.

The same for magics !!! I use 50 magics and i drain with 27