Before entering The Craw you will need to gather an allelopath blightsnail to lift the weedwhip strangulation curse. The snails spawn all along the tunnel to Skelegore and Bonewretch and can be tracked. They only appear to (and are required by) those doing the Signature quest Visions of Vetrovia: Vacrul Intentions.
Enter The Craw at ( -41, -63, 196 ) Copy/waypoint -41, -63, 196 (straight across from where you originally entered the zone) and climb the stairs.
Tank and spank for the most part. Mazza will not take damage until Porzo is dead. AOE the adds.
Exit The Craw at ( 4, -53, 158 ) Copy/waypoint 4.32, -53.31, 158.08 (lower exit door) to access the Royal Blood Halls and Cruor Keep.
Note if doing the Signature quest: Vishra appears by the Royal Bloods Halls exit; check that your journal deems you to have "seen" him before continuing.
Hail the named to start fight. Interrupts can be used to stop his casting.
Bloody Buffet - Run over the blood boils that appear to remove his incremental stoneskin.
Vampiric Hemorrhage - Joust out of range or use an interrupt when he casts. If it hits you there is a knockback and a fast-acting trauma that will kill you if not cured very quickly.
Seems to be preceded by him leaping into the air. An interrupt at this point works nicely.
Staying near the far wall may help. However the knockback throws you in random directions, sometimes while in mid-air, so is very hard to correct for.
