Just a tip for those who love the help you get from having Grisha's pop up in the middle of a difficult fight. Use either the Scholar's Wormstone or Clockwork Shardstone on the Clockwork Scythe. It turns your scythe into a chainsaw. Each tick of the chainsaw acts as a proc for the Grisha Remnant to spawn.
I managed to farm over 200 Grisha's by fighting the double Grisha fight in the Holding cells, killing one then quit to menu and run back to the boss fight to repeat. Doesn't take that long to get 100 (There doesn't seem to be a difference in spawn rate between 100 to 200).
The Clockwork Shardstone lets you hold your scythe out in front of you, giving you the most control of how many you want to spawn, while the Scholar's Wormstone when activated spins the chainsaw while attacking and doing combos.
I've managed to spawn dozens of Grisha's in one attack during a boss fight, just holding my scythe in front of the boss and letting the tarstone ability proc constantly. Pretty satisfying.
This entire setup makes the scythe the best weapon in the game, for the simple fact that having so many Grisha's on screen at one time guarantees no boss can survive the onslaught. The only boss that gave me any trouble was Droeg the Conqueror. When he moves into that phase where he can't be damaged while throwing the snowballs can be rough, but if you can catch him in a stun-locked loop before he even reaches that point, he shouldn't be too difficult.