Momentous Fall, Harmonize and Sakura-Tribe Elder would be nice additions for card draw and ramp. Eternal Witness is amazing all around and pretty much a staple in any deck that runs green.

Bloodshot Cyclops, Burning Anger, Rite of Consumption, Grab the Reins, Final Strike, Rupture, Soul's Fire, Soulblast, Xathrid Demon and Sword of the Ages can each fling your general for lethal damage.

I'm also recently a big fan of Fatal Frenzy and think it fits in strongly here. Can be used burst through with commander damage or equipped on some of your creatures you already want to die.

Also, I would replace Dawntreader Elk with Sakura-Tribe Elder. Kresh gets one less counter but it has a lot more flexibility.

The strongest play with Sakura-Tribe Elder it comes out on T2 and ramps you into your CMC4 on T3. Worst case you're paying 2 mana to give Kresh +1/+1 and get a tapped land somewhere later on in the game.

The strongest play with Dawntreader Elk is if it comes out later in the game and you're paying GG1 to put +2/+2 on Kresh and a tapped land. Worst case it comes out on T2, pops on T3, the mana it generates isn't used until T4 and you could only cast a CMC2 spell on T3.

I would place more emphasis on early game acceleration since you really want to start saturating your board as quickly as possible with sac outlets and removal for Kresh rather than providing minor mid-range boosts.

Final note, I dabbled with Zhur-Taa Ancient in a couple of my G/R decks and it always did more harm than good unless you manage to cheat it into play so you could still use mana or swing with it the turn it comes out; both of which are highly unreliable plays.

You should check out my Kresh deck for ideas. It is based around destroying everyone else's board and leaving me with a gigantic Kresh. good luck, and remember Kresh is Love. Kresh is Life..

Kessig Wolf Run is the single best land for this deck.

possibly consider Magus of the Abyss

thats a nice Sol Ring you got

with all the landfall effects you have I would suggest Scapeshift

How about Hell's Thunder? Ball Lightning Groundbreaker Greater Good?

Look for some creatures with unearth, undying, or persist. I bet those would be nice.

I suggest Doubling Season, if you're looking for a more expensive card. Also, good WinCons in my Kresh deck are Soul's Fire/Essence Harvest.

In Garruk's Wake I think would be fantastic for your deck. I have a friend who runs Kresh and it has easily won him games. Hes had Jarad, Golgari Lich Lord on the field, played Kresh, board cleared and chucked Kresh for full table lethal.

Mikaeus, the Unhallowed could do fun things in this list