Does a stunned Yasuo still trigger his 'when I attack' ability and deal his might damage?

Ruling: Yes, a stunned Yasuo still triggers his 'when I attack' ability and deals his might damage. Combat damage and ability damage are different, and stun only prevents combat damage.

Sequence:

• When Yasuo is moved to attack (such as via Charm), his 'when I attack' trigger goes off
• A showdown still occurs with Yasuo labeled as the Attacker
• Yasuo's ability resolves and deals might damage
• The stun prevents only combat damage, not ability damage

Nuances:

• Might damage from abilities is not impacted by the stunned status
• The distinction between combat damage and ability damage is critical here