Does Dangerous Duo target itself with its "When Played, Mighty" (WYPM) effect to become Mighty when played, thereby triggering Volibear's Relentless Storm ability?

Ruling: No, Dangerous Duo is not Mighty when played and does not trigger Volibear's Relentless Storm. The unit must fully resolve before its "When Played" trigger goes on the chain, so at the time Volibear checks for Mighty units being played, Dangerous Duo is not yet Mighty.

Sequence:

• Dangerous Duo resolves and enters play
• At this point, Volibear's Relentless Storm checks if a Mighty unit was played (Dangerous Duo is not Mighty yet)
• After the unit is fully played, its "When Played, Mighty" triggered ability goes on the chain
• Only after this trigger resolves does Dangerous Duo become Mighty (too late for Volibear)

Nuances:

• This applies to any unit with "When Played" self-buffs - they are not considered to have those buffs at the moment they are played
• Sett follows the same logic and is not Mighty when played