If another effect (or effects) modifies how much damage a source you control of the chosen type would deal (for example, by preventing some of that damage), the player being dealt damage or the controller of the permanent being dealt damage chooses the order in which any such effects, including the effect of Collective Inferno's last ability, apply
1 Lich's Mastery
ATTENTION: People used to clip (= cutting the edges) of these cards back in the days, to make the corners look like Alpha or Beta cards
The two Treasures you give to your opponent really do not matter if you're trying to protect your winning combo, or you're stopping another player from winning the game
And with her abilities, she will likely become a staple in some mono-blue and dragon commander decks, helping that value grow from her $15 price today
Timeless Wisdom Last week I covered the larger picture of what I would do with Gavi, Nest Warden