Can you react to ON CONQUER effects before the conquer happens, specifically to kill Draven before he gets +1 might from Qiyana's conquer trigger?

Ruling: You cannot react before the conquer happens. By the time Qiyana's ON CONQUER trigger is on the chain, the conquer has already occurred and Draven's passive ability will have already updated his might.

Sequence:

• Combat/Showdown resolves (Watchful Sentry dies)
• Conquer happens and the point is gained
• Qiyana's ON CONQUER trigger goes on the chain
• Draven's passive ability immediately updates his might (does not use the chain)
• Players can now react to Qiyana's trigger on the chain

Nuances:

• Draven's ability is passive, not triggered, so it doesn't create a reaction window
• There is no reaction window between the deathmill trigger resolving and the conquer happening
• It would be possible to create a reaction window if you had two deathknell effects or similar triggers that you could order so one resolves first, allowing you to react before the second one resolves