Scarecrone is an actually great scarecrow that doesn't require Conspiracy to be out to be good and if Reaper King dies the crone will let you just bin him and readnimate him instead of having to recast him each time. You didn't mention it in the description, but since you have Rite of Replication in the list I assume you know to use it on Reaper King to blow up 25 permanents right? Also, if you are doing what it seems like you're trying to do with the Champion ability, none of that works with Conspiracy. Conspiracy is a replacement, all your creatures with Champion lose their actual creature types and become scarecrows so you can never champion anything again. So the loops don't work

I should caveat *unless you activate Mirror Entity after Conspiracy enters the battlefield, in which case you get into layering. Or I guess you could just do it only with Mirror Entity.

Scarecrone is a deviation from the primary goal of the deck (blowing up permanents). While it is a scarecrow, I will never let Reaper King slap the grave. Too many reanimation shenanigans can occur that aren't interactive for my deck type and would ultimately cause me to waste resources on retrieval. Even if that isn't enough for you, I don't run nearly enough artifact creatures to see this as a useful option.

Conspiracy is in as a loop enabler, not to turn everything into scarecrows. The type-specific champions (Boggart Mob, Lightning Crafter, and Wren's Run Packmaster) as well as cards like Restoration Angel, Moggcatcher, and Skyshroud Poacher all become far more flexible with Conspiracy. It's primarily for assembling the combo when my primary methods fail and gets removed prior to hitting critical mass. Think Xenograft would be easier to work with?

Rite of Replication is a lovely toy. I'm aware of it's used, including how it makes Reaper King and Hagra Diabolist.

Got any suggestions for other cards to abuse?

Xenograft would seem to be less likely to nombo with other stuff since it doesn't replace the creatures types. It just seems like having so many different creatures that reference specific creature type would be clunky, instead of just focusing everything on scarecrows. But if you say it works for you then more power to you. I wish we could play in real life so I could see how it works. Where do you play/live?

Perhaps with all those ETB effects, you might consider panharmonicon. It's something I have been exploiting recently and found it to be quite fun.

Planer Bridge or Parallel Thoughts might serve better as some long-term tutors instead of one-shots.

jpsuchecki: Planar Bridge is insanely mana intensive for what it gets me and Parallel Thoughts will hose me/eat removal more often than not if I'm using it for anything that isn't removing lands from my deck, so I'll pass on both of those.

Panharmonicon is an interesting option I hadn't considered before. It works directly with all cards mentioned in my "Cards to Abuse" section. I'll fiddle with that for a while and see how it goes.

Planar Bridge is a late game card which I have always found helpful, but I can see your problem with it. I know Parallel thoughts can be risky given its problem with removal, but I have found disenchantment isn't very big in EDH.I have never had it removed.

If you like Panharmonicon, consider Mirage Mirror.

Dack's Duplicate? Clone with haste & dethrone. Not sure if your lineup needs it, but he can be extremely effective.

A hasty clone would be useful if I were looping Lightning Crafter. I may cut Stunt Double (the flash hasn't proven as beneficial as I had originally hoped) or Joiner Adept (it's been mostly a bad draw and hasn't really helped my manabase since I invested in better lands). Are there any others you'd suggest adding or cutting?

Prolly Joiner Adept, with Reaper King out the Stunt Double is also a destroy at instant speed.

Have you considered Turntimber Ranger ?

Spark Double since it's basically a non-legendary Sakashima ?