Ritual of the bitter rose.

I get the part of each ready vampire getting blood equal to the blood that is currently on a vampire being diablerized, but when burned in combat, is it the amount of blood the vampire started with in combat?

Example. Vampire A has 2 blood going into combat, and recieves 4 aggravated damage from vampire B. Vampire A takes 1st aggravated damage, wounding him. Then burns 2 Blood for the 2nd and 3rd aggravated damage and burns on the 4th aggravated damage. Playing Ritual of the bitter rose, how much blood does all your ready vampires receive?

Trigger wrote:

I get the part of each ready vampire getting blood equal to the blood that is currently on a vampire being diablerized, but when burned in combat, is it the amount of blood the vampire started with in combat?

Example. Vampire A has 2 blood going into combat, and recieves 4 aggravated damage from vampire B. Vampire A takes 1st aggravated damage, wounding him. Then burns 2 Blood for the 2nd and 3rd aggravated damage and burns on the 4th aggravated damage. Playing Ritual of the bitter rose, how much blood does all your ready vampires receive?

If you're diablerizing In combat, you're playing:

Amaranth
[Combat] Combat

Only usable by a vampire who can commit diablerie. Only usable when the opposing vampire should go to torpor. Diablerize the opposing vampire instead. Not usable by a vampire being burned or going to torpor

So, the eating of the minion is a replacement effect. "When you would do X, instead do Y"

So instead of going to torpor, the opposing minion does this:

6.5.5. Diablerie
Diablerie is the act of sending another vampire to Final Death by drinking his blood. Only ready vampires can commit diablerie. Vampires marked as Blood Cursed cannot commit diablerie. The vampire committing diablerie is called the diablerist. Diablerie is resolved as follows:

All blood on the victim is moved to the diablerist. Blood in excess of his capacity drains off as normal.
The diablerist may take any equipment on the victim.
The victim is burned (sent to his owner's ash heap). Any cards and counters on him are also burned.
If the victim was older (had a higher capacity) than the diablerist, the diablerist can be given a Discipline. His controller may go through her library, ash heap and hand to get a master Discipline card to put on the diablerist and then reshuffle her library or draw back up to her hand size as necessary. This may increase the diablerist's capacity by 1, but does not automatically give the diablerist a blood to fill that new capacity.
If the victim was Red List, the diablerist may receive trophies (see section 11).
The steps of diablerie are treated as a single unit. No effects can be used to interrupt the diablerie; effects may be played either before or after, as appropriate. After diablerie, a blood hunt may be called on the diablerist.

This is the important part for timing:

For each point of damage inflicted on a vampire, he must burn one blood to heal the damage. A vampire can burn all of his blood if needed, and doing so does not have any other negative effects on the vampire. If a vampire cannot heal all the damage (i.e., more damage is inflicted than he has blood with which to heal), he burns blood to heal what damage he can, and the unhealed damage leaves him wounded. A wounded vampire is moved to torpor after the remaining damage is handled (see Torpor, sec. 6.5).

Remaining damage is handled.
Then they go to torpor.

Your example in not amaranth-able, so you're not eating, just using RotBR on a burn. By nature of a wounded vampire burning to agg, they all net the amount of blood on the vamp when they burn. 0.

RotBR is nice with amaranth. If you dont amaranth to play it you have to get creative:

Ahriman's Demesne
[Combat] Combat

[Obtenebration] Obtenebration

[2 Blood]

Not usable the first round of combat. Only usable at long range.
[obt] Strike: 1R aggravated damage.
[OBT] As above, and if the opposing minion is a vampire and would go to torpor during the resolution of this strike, he or she is burned instead. This is not considered diablerie.

Hope I referenced enough rules to cover whatever else you would need RotBR for.

What about using the superior part of Decapitate? If a vampire going to torpor, burn the vampire instead. RotBR says, usable in combat of an enemy is burned.

Burned and diablerized aren't the same right?

I think I get it, Decapitate would need to be used with say 1 agg damage. So if vampire had 4 blood, takes 1 agg damage, going to torpor, play Decapitate, is burned, play RotBR, each ready vampire gets 4 blood since vampire burned with 4 blood on him?

Burned is indeed different from Diablerie. Vampires burn through diablerie, yes, but there are other ways to burn minions as well (Decapitate and massive amounts of aggravated damage for example).

Ritual of the Bitter Rose only cares about diablerie. Burning is irrelevant to the Ritual.

Ritual of the Bitter Rose only cares about diablerie. Burning is irrelevant to the Ritual.

Now let all of us contemplate on why copypasting relevant card texts to a Rules post is actually relevant. Please always start with copypasting from Card Lists.

Name: Ritual of the Bitter Rose
[Jyhad:R2, VTES:R, CE:R]
Cardtype: Action Modifier/Combat
Each ready vampire you control gains an amount of blood from the blood bank equal to the amount of blood on a vampire being burned either by diablerie or while in combat with this vampire.
Artist: Drew Tucker

Trigger wrote:

I think I get it, Decapitate would need to be used with say 1 agg damage.

OT, but Disarm is often an easier way to trigger Decapitate, e.g. if a vamp with POT is wearing a Leather Jacket, they can burn someone off an unmodified hand strike.