Black cane's pretty alright, but you really need other shadow weapons (coughthethrowingdaggercough) to take advantage of 'em. Fortunately at least one of said shadow weapons (it might be the throwing dagger just saying) is pretty friggin' beastly so it's quite reasonable to run with at least one or two cane minion pairs to keep the shadow weapon buff (i.e. a +100 damage bonus for the shadow weapons, including the summons, on top of some other stuff) topped off. The non-ranged dagger throwing thing (the whatsit and chain thing) is also surprisingly useful if you ever manage to actually get the damn thing to latch -- adds some sustained damage and slows the moment of most things, some bosses included.
Currently screwing around trying to figure out what does the most DPS while procrastinating about finding some way to tank devourer of gods hits, myself. Finding out painfully that throwing apparently shitkicks every other damage type at the point I'm at. Beats them into the goddamn ground. Lucky to break 2-3k/s with everything else, idle in the 4-5k with shadow dagger + throwing book + white dwarf, and using the providence drop (molten amputator, which you'd think would be sexy for the 300ish base damage, but it's more the lava pods it spews everywhere when it's landing hits) instead will regularly spike into five digit DPS.
Apparently when you take an item that spawns projectiles every time it hits something, moves like a normal (if huge and wall piercing) boomerang (i.e. occasionally will get on the other side or inside your target and hover for a bit, damaging all the while), an item that duplicates what seems to be all of that for fractional damage, and % max health damage per instance of critical damage on top of it all, your damage output goes bugnuts and every bloody other thing you can get your hands on pales in comparison.
... the sad thing is it's annoying, since even with fairly sustained five to ten thousand damage per second it still takes too ruddy long to kill some of these friggin' bosses. Ravager has over a million HP between its parts (all of which must die) post providence. Also it might drop the solution to my devourer problem (an accessory that halves contact damage), assuming it'll drop it before I get fed up and figure out how to edit my max health value instead. So it's somewhat irritating to keep chewing through the freaking damage sponge blighter.
E: Huh. So the crazed contraption seems to live up to its name. The thing fires a random shot made from, as near as I can tell, anything. Anything. Including summoning weapons, pets, and armor set effects, and it's hard to tell if any of that actually counts towards your summoning limit. After shooting it for a while, I now have the stardust stand thing hovering on top of me, two eyeball spring pets, a green rabbit, companion cube, three different lighting pets, the tiki spirit, a tiny dinosaur, tiny corruptor, snowman, parrot, some kind of tree thing I'm not aware of where comes from, a black cat with wizard hat, corrupted mini-net thing, and a floating heart, all following me around. On top of the metroid and zap ufo I normally have. And the elemental axe summons. The screen is... noisy.
E2: Aww hell, what I was trying to test came up positive. The thing can shoot block destroying projectiles, too. So if for some ungodly reason you want a dozen mostly useless decorative pets following you around, be careful where you point the thing as you're spamming shots to get them to show.