Confused about runes

[bibbo]

Are runes supposed to stack over skill or replace that skill ?

Shock Pulse: Release a medium range pulse of 3 unpredictable charges of electricity that deal 105% weapon damage as Lightning.

With Fire Bolts: Cast bolts of fire that each deal 136% weapon damage as Fire. ( replace? )
With Explosive Bolts: Slain enemies explode, dealing 70% weapon damage as Lightning to every enemy within 10 yards. ( stack? )

Its a bit confusing.

[capnlarge]

The rune values don't stack on top of the existing skill. They simply modify the original skill to have the properties listed.

[Darkmere]

Yes and yes. it changes based on rune/skill, there's no single rule that defines them all.

Some just add +%damage to the base skill, others completely change how the base skill works, others change the damage type, others make it cheaper to cast. Every rune is different.