Posted this on your decklist, but I'll post it here as well.
Protean Hulk, pretty obvious suggestion. You probably don't play it due to power concerns but felt I'd mention it anyway.
Panharmonicon, you got a ton of creatures with ETB's that would benefit from this, might be too win-more, but should be pretty good.
Ashnod's Altar, often just straight up better in combination with Nim Deathmantle. Definitely worth running next to Phyrexian Altar.
Stoneforge Mystic, on the note of Nim Deathmantle, it's just so good you might as well add an additional tutor for it. Can also get Skullclamp which is an amazing card.
Deranged Hermit, a cheaper alternative to Avenger of Zendikar for infinte ETB/LTB/Mana with Nim Deathmantle and Altars.
Blasting Station, probably the best way to win with your infinite combos.
Mentor of the Meek, good draw engine. So many small creatures that keep on coming back, this will draw you quite a lot.
Woodfall Primus, excellent tool for repeatable removal. Can easily win the game with stuff life;
Solemnity, an excellent infinite combo piece with cards like the above Woodfall Primus, and Kitchen Finks. They will just keep on coming back infinitely. Vizier of Remedies and Melira, Sylvok Outcast also work similarly.
Restoration Angel, Felidar Guardian 2.0, also allows for an infinite loop with Felidar + Restoration flickering each other forever. With Panharmonicon you can suddenly flicker all permanents infinitely.
Selfless Spirit & Dauntless Escort, excellent tools to protect large boards.
Boonweaver Giant, for infinite combos with Pattern of Rebirth
Angel of Glory's Rise infinite ETB's with Saffi and a free sac outlet.