I like the idea of the deck, but is there any reason not to make it Modern legal? It's just a question of switching out the tutors for different ones like Spoils of the Vault. And, since you're already in blue, you could add some cantrips like Telling Time or Anticipate. They could help get the combo out as quickly as possible.

just saying vamparic tutor and imperial seal are restricted

You need to give it unblockable. Distortion Strike or Aqueous Form

Do you think there's a way to make a Blue/Green only version of this deck with more counters like Remand and Dispell instead of the tutors?

That could definitely work laggaprone. It would just produce controllier deck with much longer games.

Cut Shimmering Grotto and City of Brass for fetches for a more reliable manabase. Unless you are going for a budget deck that is.

You should have more than 6 fetches

Add two Overgrown Tomb, Two Breeding Pool, cut all basics except one Forest and one Island or two Forest, and replace lost landslots with Polluted Delta and Misty Rainforest. This will ensure a more reliable manabase and overall game. This is hinging on the fact that you want to be a combo deck though.

You should consider adding some Flourishing Defenses. When you put a -1/-1 counter on Devoted Druid, put a 1/1 Elf token