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Can you use the ability of the Wand of the Wych Elm to reroll an attempt to dispel a Remains In Play spell during your own magic phase using your power dice? This is as opposed to making the attempt during the opponent's magic phase using your dispel dice.
Wand says any dispel attempt. So yes, you can use it when dispelling remains in play spells.
I am right 94% of the time, why worry about the other 3%.