Crawlipede thing it's one of my favorite enemies, no other enemy makes you change up your playstyle in an event as much as crawltipede, though the other enemies in the solar pillar pull crawltipede down
Morning wood has some of the most useful items in the game.
Necro scroll- a very strong accesory on its own, and it can be upgraded.
spooky wood- makes spooky armor, both a decent set on its own and good for mixed sets
witch broom- best infinite flight mount, very useful if you don't have soaring insignia yet
stake launcher- incredibly strong ranged weapon, hits hard, fires fast, mows down old ones army, and can even kill Betsy if you have enough damage buffs.