From SuspireWiki

The Fontal Rituals are a set of three rituals, commonly practiced by the Ordo Dracul that allow them to tap the power of Fontal Nests to provide themselves with arcane benefits.

All of these powers require a vessel - either a mortal or one of the Kindred into which mystical power is channeled and then released in the form of feeding of bloodletting. This, naturally, can have a noticeable effect on the ritualist's humanity.

Arcane Vitae allows the ritualist to channel mystical power into their Disciplines, making all disciplines that require vitae more powerful and effective.

Drink the Resounding Blood allows the ritualist to tap into the "resonance" of the Fontal Nest, to use it for their own ends.

Feast of Blood allows the ritualist to slake his thirst on the vessel with ease by empowering the vessel's vitae.