Whatever the OP wants, I'm down for it.
Personally I am fine with just dramatically doing duels _within_ the RP. I mean, this is a role play, not like we are virtually trying to draw each card and this and that. But pretty much I'm fine with whatever the OP is good with.
I personally think Monster Reborn and Change of Heart are fine, but whatever the majority decides is fine with me.
I mainly care about character interaction, fun story and stuff like that. If people want to do actual duels outside of the RP, I think that would be most practical. But whatever works!