Am i reading Power Siphon's details correctly on the wiki?

It states that linked with Lmp/gmp it will still only gain one power charge per attack, despite how many enemies it kills. Am i reading this right?

So if i attack a mob, kill 7 enemies on 1-2 hits, i will still only get 1-2 power charges?

I'm making my first wander and i was thinking of getting power charges in this manner with just a 3L. Looks like i'll have to re look, and i dont' think i could support herald of thunder.

description is correct - no matter how many kills -> 1 power charge per attack