I realized Esoteric Duplicator might actually be a crazy combo with Spirit-Sister's Call. Worth a try?
I think Threefold Thunderhulk has the strongest synergy with Sister and Duplicator. Sister enables the sacrifice of the Thunderhulk, and Duplicator enables making a duplicate of it (next end step). Later, sac a gnome to Sister to get the Thunderhulk back.
Last time I played Sister I liked it with The Millennium Calendar All Will Be One meme combo. Calendar's bad value is minimized a bit by Sister's ability to swap it out for a big artifact like a Thunderhulk or Portal to Phyrexia. Having some lurking big artifact threats helps make the opponent second guess when to spend their artifact removal. If they hold off too long All Will Be One might ambush in to one-shot the opponent off the Calendar doubling.
Zoetic Glyph can also turn the Calendar into a threat, or amplify the Thunderhulk threat. Adding in some Scene of the Crime artifact lands is another tempting Glyph target, and Duplicator can work on it too.
If we want to play some enchantments around the Sister, then Spellbook Vendor gives some repeating enchantment making to sac with. One with the Multiverse is a fun payoff to return.
The Restoration of Eiganjo
helps get mana, discards good Sister targets, and is a fair Sister target itself so you don't have to hold it back in combat even if the opponent has good blockers.
Sister can also call back Battles. Battles also make counters for the All Will Be One. Invasion of Tolvada
is a good backup reanimator. Invasion of Gobakhan
or Invasion of New Capenna
seem workable (and can be brought back by Restoration).
I think I like The Key to the Vault as another backup way to get the big payoff cards into play.
Mana costs for this pile is really harsh. I'm putting in Goldhound to help take the edge off. It's decent with Scene of the Crime actually. With Portal to Phyrexia out, it's ok to sac it for mana because you can get it back. Restoration or Duplicator or Sister can get it back too in different setups. Glyph makes it a 5/4 menace threat or Hound can just trigger the Discover plus a mana.
But adding Goldhound means turn 1 red mana is in dire need. I don't see any way around it but to put in Thran Portal and Mirrex. The fast lands and the slow lands and the tri-lands are just not cutting it. To make this pile work the way it wants to, the lands have to almost always come in untapped, and they have to almost always have color-flexible mana. And there has to be at least a cluster of Plains for the Restoration. So pain is the only option. Thran Portal and Forgotten Monument and Captivating Cave and Volatile Fault are going to be the bulk of the land cards.
Still, this deck is super hard to pilot. The defensive options are terrible. Navigating a true curve without fumbling requires advanced math brain. This is super jank.
