Something nobody done before.
+How about an ultimate showdown mod? You have one day (24min) to fight each boss/event of the game (in addition active mods). One boss and one event always at the same time. If defeated one the next stronger appears. The normal units could spawn like in the Old one's army event (but always in same order). Like in Pumpkin/Frost moon you get points for defeating many enemies in short time. Different player could compare their results. That would help to find the true 1337-uber-Terraria-g4m0r.
here some more ideas (not updated for a while):
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