I'll be honest: while I really like this deck, I think you're not running nearly enough lands.
With
Agadeem's Awakening, you have 34 lands, but one of them is
Cabal Coffers, which shouldn't be counted as a land since it doesn't produce mana without
Urborg. By drawing some sample hands you can see that often you end up with openings with 2 or less hands and no 2-cmc or less ramp, which is pretty risky to keep.
I usually aim for at least 37-38 lands (counting MDFCs) plus 10-12 ramp cards, so my suggestion would actually be to cut 3-4 non-lands and include
Bala Ged Recovery,
Malakir Rebirth,
Yavimaya, Cradle of Growth and
Dryad Arbor, which works perfectly with
Green Sun's Zenith and is synergistic with Meren.
Some cards that I would
consider for cuts:
Moonlight Bargain (not efficient enough for 5 mana)
Grisly salvage (non-creatures should be as few as possible and this doesn't do enough)
Sheoldred (if you're going for a combo, she is not really needed and she's a bit slow)
Damnation (4 board wipes are a bit too much and
Damnation is the worst of the bunch).
Also I'd suggest you
consider Living Death, maybe instead of
Culling Ritual. I know Ritual is a bomb in the right meta, but
Living Death is one of the best cards in Meren and can straight up win games.
Hope this helps!