Boon Harbinger

Transfusion is the reason to run Staff: your marks become ally-triggerable, and the ally who trips one gets healed and picks up vigor and Stability. That is not a downed-pull — Ritual of Life is the rez trait, casting Lesser Well of Blood whenever you start reviving someone and making wells of blood revive every pulse — while Life from Death heals everyone around you each time you leave shroud. Deathly Haste is why you sit in Harbinger Shroud at all: it pulses quickness and fury to you and the allies near you. Twisted Medicine shares your elixir boons with everyone in the impact radius and converts vitality into concentration, and Bolstering Brew adds protection to every elixir — so Elixir of Ambition, which gives you every boon in the game, gives them to the group too.

Full Minstrel's with Leadership — toughness, vitality, healing power and boon duration. The vitality is not dead weight: Twisted Medicine converts it into concentration, and Alchemic Vigor heals you per stack of Blight, which is the cost of standing in shroud. Absorption steals three boons when you interrupt — Reaper's Mark is the fear that triggers it — and Nullification strips on flank. Energy keeps you dodging out of the bomb you are standing in to rez. Astral Ward needs two signet activations to pay out and Signet of Vampirism is the only signet on the bar, so it is the slowest part of the set.

It is not helpless on its own — Elixir of Ignorance is a stun break that gives you resistance and protection — but it kills nothing, and none of the trait line does anything without allies standing in it.

If the squad already has its heals covered and wants damage or strip pressure out of this slot instead, take Scourge.