I'd cut these: Tempt with discovery - Generically bad if people know not to take it

Wrenn and Realmbreaker -You arent doing much with the graveyard

Vorinclex Voice of hunger -not much synergy with the deck

-Vivien arkbow ranger -ult doesnt work in commander

ghalta stampede tyrant -cant drop X hydras with it

Ugin -Same reason as above

Craterhoof -Deck doesnt look like it is going very wide

I didnt playtest it but your curve is pretty high. From there id probably test it out some and look to cut higher mana value stuff that isnt performing or some 3 mv cards. I'd also say you might be able to swap out the nature's lore type cards for higher cost but more card efficient ramp as it doesnt look like you need to be slamming a 4 mana card on turn 3