Tengu format ruling
Vengeful Servant

Card effect (current official text)When control of the equipped monster changes, inflict damage equal to its original ATK to its new controller.
Rulings
- The effect of "Vengeful Servant" starts a chain when control of the monster switches.
- If a Continuous Effect would destroy the equipped monster first (example: an equipped "Thunder Nyan Nyan" switches sides and is destroyed immediately), then the effect of "Vengeful Servant" does not activate and it does not inflict damage.
- If "Remove Brainwashing" is active and a monster equipped with "Vengeful Servant" switches sides, that monster immediately switches back to the original controller.
- The effect of "Vengeful Servant" then starts a chain (and only activates once, in this case) and the original controller of the monster takes damage.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Tengu forum — sourced change requests get reviewed.