Not a novel deck concept nor a novel general to lead it, but it's good to have a deck on hand whose gameplan is to use everyone else's cards to win (it automatically scales to the group you're playing in, more or less), and I like sneaky little Thada Adel better than big bad Memnarch.
Cathedral of War: Thada's small and often attacks alone, might as well get some extra damage in.
Rogue's Passage: Because sometimes, somehow, someone might not have an Island.
Arcum Dagsson: At most tables, there will be someone running Solemn Simulacrum. Steal their Simulacrum, find a land, sacrifice it, draw a card, find an artifact for free, and gain tons of value.
Seasinger: Yet another hillariously awkward old card that suddenly becomes pretty good under the right circumstances.
Streambed Aquitects: One of those cards that's an auto-include support card for certain generals and useless anywhere else.
Vanishing: Mono-Blue doesn't have a lot of generals that can do Voltron especially well, but the ones it does could benefit from this.
Drafna's Restoration, Time Spiral: Restocks libraries to be raided again. Drafna's Restoration can also be used offensively to give an opponent dead draws for several turns if all their mana rocks died somehow.
I think you need more clones. Sculpting Steel, Phyrexian Metamorph and Phantasmal Image. I also suggest running more mana rock accel. You want thada out asap. Another quick bit of advice is to run the combo pieces to other artifacts you might commonly pull out of people's deck lists.
I don't think I'm going to use a lot of advice that would benefit a competitive 1v1 list for a non-competitive multiplayer list, sorry. The difference between Thada T2 or T3 probably makes all the difference 1v1, but is going to matter maybe 1 out of every 50 multiplayer matches, so I don't have any plans to clog the deck up with mana rocks I could in theory steal from everyone else. I also don't care to plan ahead to complete combos; I have enough decks where I know the line of play to win well enough, I'd like a couple more where the path to victory isn't always completely clear.
Also, Sculpting Steel and Phantasmal Image are on the list already.
But the point of Vanishing isn't to use phasing (well... part of it is), it's to have something to respond to removal with. Teferi's Veil leaves this big gap of protection.
I've never liked Whispersilk Cloak that much. There should be enough ways of being unblockable (turning lands into Islands), and Swords of X and Y are a primary theft target, which give some degree of unblockability. Although I might put in a Rogue's Passage.