In terms of synergy, consider: Titania, Protector of Argoth, to profit off sacrificed lands Crucible of Worlds or Ramunap Excavator to keep the land train going Scapeshift or Crop Rotation for explosive plays Greater Good to bin huge creatures, then cast them again from the graveyard for a single land This card wants to be in any deck that flirts with graveyard recursion or land sacrifice
Jackal, Genius Geneticist Jackal, Genius Geneticist might be the weirdest +1/+1 counter commander
And if you really want to break things, play Ashaya, Soul of the Wild to turn every creature into a land, making them infinitely recastable
In general, you can look at what makes Uril, the Miststalker decks tick and copy some of those tricks
Translations obtained via Citizens of Lorcana
Completing the cycle of mythic rares, there's Emeritus of Abundance (Regrowth), Emeritus of Conflict (Lightning Bolt), and Emeritus of Truce (Swords to Plowshares)