If a unit buffed by Master Yi's leader ability (for being alone on a battlefield) is later joined by a hidden card being flipped, does it lose the +2 buff?

Ruling: Yes, the unit will lose the might bonus from Master Yi's legend ability when it is no longer alone on the battlefield.

Sequence:

• Unit is alone on battlefield and receives +2 might from Master Yi
• Opponent attacks that unit
• Hidden Pakaa Cub is flipped to the battlefield
• Unit is no longer alone, so it immediately loses the +2 might bonus from Master Yi