Obelisk of Urd seems kind of unnecessary - What about Chord of Calling? Possibly Domri Rade and Descendants' Path.

I would recommend changing the City of Brass for a Mana Confluence and possibly running an Urborg, Tomb of Yawgmoth to help the Sedge Sliver and those lands together can get rid of the pinging from tapping

Hey -Akhlys-, that is actually really smart using Urborg. I swapped the Brass for Urborg, I feel confluence though is unnecessary now with Urborg. Thanks for the suggestion, really helped.

Adaptive Automaton, Mirror Entity, Bonescythe Sliver, Gemhide Sliver, Venom Sliver and Coat of Arms could all serve useful.

From looking at the list, I really like it, and there are some rather troubling inconsistencies that I would probably imagine you would run into in game. First off, the way the mana split is done here, this deck really is a 5 color deck. Which where that's great and all, we will always have to have the mana to do it. I like the idea of shifting towards a certain 3, so we don't have to run every color shockland at once. How would we do that? I don't think you need the Ghostly Prison whatsoever, and it would be safe to bump up the AEther Vial count up to 4, and the Collected Company count down to 3, as we are never going to use all 4 in a game, and having 4 of a 4 mana card with our land base can be hurtful as we wont always be able to cast it. Sliver wise, I see a lot of people run the Galerider Sliver route which is absolutely fine, we will rely on blue as one of our main colors so we can hit off the turn one Galerider frequently. Going this route, I would shave off the excess Slivers you don't really need and streamline to sticking to 4 colors, and using the 5th mainly for sideboard cards. I just posted a sliver list specifically for you, just to show you how I would approach the changes - feel free to check it out and see it if helps.

I tried the coco-less version. is fast enough to kill a valakut deck by turn 4 (before they got 6th land.

I feel that with cloudshredder sliver, speed up the deck. and unsettle mariner still debate-able vs difussion slivers

issue having is play against hoogak and tron deck.

Solution for hoogak deck, play more darkheart sliver and mindlash sliver in the mainboard, and unsettle marriner to taxes them (prevent them to mill us down)

Solution for tron deck, play telekinetic sliver sideboard