Does Reckoner's Arena trigger Yone, Blademaster's conquer ability even though the battlefield is not open because Yone is already there?

Ruling: Yes, Reckoner's Arena triggers Yone's conquer ability even when the battlefield is not open. The card activates conquer effects by skipping their trigger conditions entirely.

Sequence:

• Reckoner's Arena causes you to hold a battlefield (not conquer it)
• The card activates all conquer effects, bypassing their normal trigger conditions
• Yone's ability is placed on the chain and resolves normally

Nuances:

• Conquer abilities have two parts: the trigger condition ("When I conquer an open battlefield") and the effect ("deal damage...")
• Reckoner's Arena skips the entire trigger condition, including any additional requirements like "open battlefield"
• If Yone's ability were phrased differently with the open battlefield requirement as part of the effect (e.g., "When I conquer, if I conquered an open battlefield..."), then it would not work with Reckoner's Arena
• Once a triggered ability is activated and on the chain, nothing in its original trigger condition prevents it from resolving