Can the Raven Queen's Blessing eldritch invocation for warlocks (from Unearthed Arcana: Warlock & Wizard) heal a dying or stabilized ally at 0 HP, thereby waking them up early?
As unreliable as this would be in a combat situation, I'm curious if this works by RAW.
When you score a critical hit with your eldritch blast cantrip, pick yourself or an ally you can see within 30 feet of you. The chosen creature can immediately expend a Hit Die to regain hit points equal to the roll + the creature’s Constitution modifier (minimum of 1 hit point).
Questions have been asked about spending hit dice at 0 HP, but these are about using them in the context of short rests.