Yone

No, you will not. The main thing you need to know is that activating a conquer effect such as the Reckoner’s Arena effect is the equivalent of checking the condition of all of the specified conquer effects, as if a conquer had occurred at Reckoner’s Arena. Any triggered abilities of units at Reckoner’s Arena that trigger on conquering will see a conquer event occurring, but they will still need to check their other conditions in order to go on the chain.

In this case, the rest of Yone’s conquer effect condition is “...that was previously uncontrolled,” and since the battlefield wasn’t previously uncontrolled, Yone’s ability will not trigger.

Note that no actual conquer occurs—we’re simply treating the game as if a conquer had occurred at that battlefield for the purposes of the specified abilities. In Reckoner’s Arena’s case it specifies units, so only units with conquer effects at Reckoner’s Arena will see this conquer event and potentially trigger.

(We recognize the rules for “activate” in the way discussed above are underdefined. Expect further revisions in the next rules update.)

Source: Riftbound: Unleashed Rules FAQ and Clarifications

Forgotten Monument works differently from Tianna, and we agree that’s confusing. That’s part of why we decided to issue errata for Tianna (and not for Forgotten Monument).

Forgotten Monument completely prevents the process of scoring there. That means no conquer triggers, no hold triggers, and no points from doing those things. “Extra” points such as those from Renata Glasc, Mastermind are unaffected. You can still gain control of the battlefield following a showdown—you just can’t conquer it.

Yone, Blademaster

Source: Riftbound Spiritforged FAQ

Yone’s current text is a little, well, open to interpretation. A strict reading suggests that he can never trigger at all—once you’ve conquered a battlefield, it’s no longer open—but obviously that’s not the intent. We’re tweaking his text to cue off the control status of the battlefield immediately before conquering it. This means that he works as intended, triggering at the end of a noncombat showdown in which he conquers. It also means that he now triggers in “surprise defense” scenarios, caused when units move around during showdowns and you wind up defending a battlefield you don’t control.

Yone, Blademaster (revised text)

[Weaponmaster] (When you play me, you may [Equip] one of your Equipment to me for [A] less, even if it's already attached.)

When I conquer a battlefield that was uncontrolled, deal damage equal to my Might to an enemy unit in a base.

Source: Riftbound Spiritforged FAQ

Current wording

Previous wording

Source: Riftbound Spiritforged Errata