I think Abyssal Persecutor would be awesome in your deck -- he tramples, beats hard.. and you have an easy way to get rid of him (and go for the throat maybe). I know of a birthing pod deck very similar to yours, more green/white, but much is the same.. I think the single sheoldred is okay too, but it may do better to keep in the 3-4-5 cmc range for your birthing pod.
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