I'm thinking Vanish and Assassinate are a Must. Maybe Sprint at 1. . . eh, maybe 2 sprint also. Hallucination may be helpful since it can get you huge spells from other classes, as Rogue doesn't have too many big spells.
Important to note that Doomerang isn't affected by Spell Damage and doesn't summon a 1-cost minion while you control Atiesh.
What are some Ideas you all have? I have a feeling this will be a bit gimmicky, but a TON of fun!
Doomerang's weird; it isn't effected by the spells you'd think it would be, although I've found it works exceptionally well with Perdition's Blade and Edwin VanCleef. Really great for combo-heavy cards.
Maximizing the value of Medivh, the Guardian requires you to A. have high-cost spells of your own, and/or B. "acquire" said spells. You've listed off the main Rogue spells, so beyond that a burgle package could provide you opportunities to generate non-class spells. Hallucination, Swashburglar, etc. You could even consider Lilian Voss, to transform cheapo-spells into better ones.
It turns out, Sprint is not that good when you want to play Runeforge Haunter in the same turn, hence the move to Thistle Tea. Also this deck plays a lot of spells and getting copies of everything except weapons is great, (and even sometimes that's fine) so we play Arcane Giant and Mimic Pod.
Any suggestions for something I can take out to put patches in? Early game is still kinda nonexistant . . .
Such original and fun idea! Preps for all involveds.
Now, concerning the current list:
I know the idea is to generate great value with multiple Atiesh and big spells, but you need a realistic ratio of the stuff from your deck. I'd change the 2x Thistle Tea/1x Mimic Pod to 1x Thistle Tea/2x Mimic Pod instead.
Doomerang havin synergy with more than just Atiesh is nice as well, I thought first in cutting one copy of either Shadow or Perdition's Blade for the Patches you want to add, but they actually are great help to control the board on the early game. I guess I'd cut Assassinate or a Sap, as both are kind of redundant and more mid/late game oriented.