Hiya,

If you "Invoke Cambrinth 10", it overrides "invoke cambrinth spell" (from dedicated cambrinth feat) and cyclics drain mana instead of your spell.

charge my mana 20
You harness a moderate amount of energy and attempt to channel it into your cambrinth manacle.
You are able to channel all the energy into the manacle.
The cambrinth manacle absorbs all of the energy.
Roundtime: 4 sec.

R> invoke my mana 10
The cambrinth manacle pulses with Arcane energy. You reach for its center and forge a magical link to it, attempting to ready 10 mana streams for your use. You manage to attune yourself exactly as you intended to.
Roundtime: 1 sec.

>invoke my manacle spell

The cambrinth manacle pulses with Arcane energy. You reach for its center and forge a magical link to it, readying all of its mana for your use. By directing your focus, you ensure that mana is drawn only when spells are cast.
Roundtime: 1 sec.

R>
Your cambrinth manacle thrums softly as it discharges some of its power to maintain your spell.
Your cambrinth manacle thrums softly as it discharges all its power to maintain your spell.