Guild Wars 2

I am new to necro thats why asking a basic question > What stat does life siphon ( Dagger #2 skill) heal and damage affects this skill?

Yes, although that also applies to all Necromancer siphoning now, traits and skills both.

I assume you mean how do you make the healing and damage numbers larger, in which case the healing half scales off healing power, and the damage off power, and can also crit with precision/ferocity.

Bhawb.7408:

I assume you mean how do you make the healing and damage numbers larger, in which case the healing half scales off healing power, and the damage off power, and can also crit with precision/ferocity.

are you talking about dagger #2 specifically? just to be sure