Forum:Mask Change Vs. Solemn Warning

So, since the "...send it to the Graveyard, then Special Summon 1 "Masked HERO" monster from the Extra Deck with the same Attribute" part of mask change activates at resolution, do I need to tribute my monster if my opponent uses solemn warning on mask change. Also, they have to activate solem warning before or after I target my monster?