There are plenty of cards like Rhythm of the Wild and Fires of Yavimaya that can give haste to all of your creatures if you go down that route, so all you need is some sweet creatures to combo with it and Im sure that you can find some
Battle Mammoth Two Green mythics back to back
Astrologian is a FINAL FANTASY XIV job whose practitioners draw cards that depict the constellations of the night sky, then play those cards to buff their allies
If you can put some poison counter-generating cards like Infectious Inquiry and Ichor Rats into your deck, Yawgmoth can proliferate those as well, though this does risk making you public enemy number one at your table
It can even stand in for narrower answers like Stony Silence or Ancient Grudge against Affinity and Lantern, doubling up against the tribal aggro decks, though you do lose the splash damage Stony Silence brings against Tron, Krark-Clan Ironworks, and Ad Nauseam
Kalamax will hook you up with an extra copy of yours