Heretical Grinder 9/9 just melts things. Just remember to pack along a few magic restoration items.
I think i'm at the final two bosses now, but a tad underlevel/equip. Doing a bit of farming tonight to even the odds, will probabaly kill them tomorrow night or this weekend.
I've killed all the bosses, have 100% of the map, and 100% of the enemies. I'm also fairly sure I've found all the secret walls and passages. Not all of them go towards 100% of the map, but between the fairy and the reveal hidden walls shard, I'm fairly certain.
I finished all the bosses at around lvl 50. I also had all my gear focusing on Luck for the entire game to make farming easier. So I'm not doing near as much damage and am not as tough as I could be.
You can only get 5 of the Silver Knight and Shortcut shards in a run.
I currently have 112 Luck, and that helps with farming.
Enemy number 44 was a huge pain in the ass to find. It was just dumb luck that I stumbled across it. He's on the train and you need to sit in the chair to find him.
You do not need to sit and wait on him. He runs on a timer, so you only need to wait a certain amount of time and then sit on the seat by the open window to spawn him. It's the only spot you can sit, so finding it isn't hard. You'll know he's near when you start seeing the eye animation.
So clear out the train, then go back and sit and it should be close to when he appears if you weren't in a hurry. Alternately, you can just ride on top of the train and hit the passing lampposts to farm gold. The time is slightly longer or shorter depending on what direction you're going. It's shorter on the trip away from the castle. That doesn't matter much as the fastest way to farm is to just take the trip back and fourth.
He is almost a mini-boss. He takes a ton of hits, stun locks, and inflicts curse on you. I usually just use the time stop ability to get behind him and pound on him until he's dead. He drops the curse resistance shard. On the plus side, his shard drop rate is three times higher than most other shards. You can also just get on top of the train car and range attack him to death.
Enemy 44 is the absolute worst shard grinding enemy in the game. It only appears in one place in the entire game and takes about three minutes per attempt at least because of how you spawn him.
Most other enemies you'll need to farm have at least one spot where they appear right inside a door. So you can just run in and out of a room over and over to farm them.
Beating the ninja guy's race in the last area also helps a lot with endgame farming. As I mentioned, you really only have to beat him once, and using the armor that makes you invincible to spikes and such makes him stupid easy. After that, just use his own power against him to get the other 8 shards.
The run power does a small amount of damage to enemies you run into, and you can run right through a lot of them. Some will stop you, but you can usually just keep going immediately after. You can farm small weak enemies by just running back and fourth over them later in the game. This is useful against frogs, and the flytrap enemies.
The homing arrow shard is super useful throughout the game. It makes getting certain shards and such much easier. It's probably the best offensive spell in the game, as it uses a small amount of magic for the damage it does. Plus, it's a homing attack.
Sword whip is also useful for grinding for shards and materials. It's not as powerful as the Encrypted Orchid, but once you're strong enough that one or two hits kills most things, the reach it has makes things go a little quicker in some area.
The fully upgraded bit coin pistol is also pretty powerful, but you need to give up some luck to make the most of it. With the right gear it's extremely powerful. There's a hat that gives you unlimited special ammo so you can just use diamond rounds forever, and using gear that increases attack speed makes it God tier.