Hello,

I have had this question in my mind for a while and I haven't been sure how this should be played. In melee if I use my Rhoynar emissary on a character that opponent controls, then attack another opponent who the first one is supporting. When the challenge goes uo should the opponent now "support" with the character since it is eligible to be in the challenge? How far will the eligible word on Rhoynar emissary go?

The Emissary's effect only applies to challenges in which the controller is an attacking or defending player. The Emissary cannot force someone to be a part of a challenge that they do not want to be a part of.

So, in your Melee scenario: Since "supporting" for the other player is optional, the supporting player's characters are not actually eligible to defend the challenge until the player decides that they want to take over the role of "defending player." That means the Emissary's effect cannot make the supporting player declare defenders.

However, if the supporting player does decide to declare defenders in that challenge, if the character hit by the Emissary can defend in that type of challenge, it must be one of the characters declared.