When activated, sacrifices your summoned demon to grant you an effect that lasts $18789d.  The effect is canceled if any Demon is summoned.

Imp: Increases your Fire damage by $18789s1%.

Voidwalker: Restores $18790s1% of total health every $18790t1 sec.

Succubus: Increases your Shadow damage by $18791s1%.

Felhunter: Restores $18792s1% of total mana every $18792t1 sec.

Felguard: Increases your Shadow damage by $35701s1% and restores $35701s3% of total mana every $35701t3 sec.