I've had some success with this rotation-proof Standard 21 tempo deck in mono blue. It's just really fun to play when it works, and even when fighting losing battles it can regain some surprising ground with Threnody Singer and combo with Barrin, Tolarian Archmage
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Escape Protocol
. The finisher here is more or less Voracious Greatshark, which also can be flickered via Protocol for a 2-mana cycle/counterspell. If you happen to stick two Protocols, a single Barrin can upset an entire board state very quickly. The multiple triggers from Protocols go on the stack without targets, and a seperate ability goes on the stack when you pay {1} in which you choose a target. So, you can blink the same creature twice.
Witching Well can be flickered as well for a scry 2, and its card draw ability can save some games in the late.
The ideal game plan is to tempo a bit with a Singer and hopefully Barrin, get a Protocol down and lock the board state with Barrin and a Greatshark. The question early game in my experience is often whether to hold cycling cards or try to find important pieces.
Mystic Sanctuary is very good obviously, and Threnody Singer is a champion IMO.
I have not even thought of what to do against a creature-light deck. The shark catches artifacts, and Barrin planeswalkers, but when I played this deck against control decks with sweepers it was Simic in Historic with Frilled Mystic instead of shark, and he would come back down and counter the sweeper.. I don't know that dodging targeted removal and having a lot of flash creatures is quite enough to be confident. Neutralize might do it, but the rest of the deck seems like wasted potential. Feel free to let me know of any sideboard ideas for this type of matchup.
The great thing about this deck is that I have cast every single card in games. There is no throwaway cycling card without use. I have cast Startling Development often enough with decent results, possibly more often than Neutralize. Frostveil Ambush is good to have just in case your permanents are removed. Boon of the Wish-Giver is essential.
Edit: I will be updating this list with sideboard ideas soon. I'm not always the best with sideboards and I feel like throwing away a Hampering Snare early game against aggro could be a difficult card disadvantage but possible while adding another creature. Faerie Vandal seems nice, but I'm not sure about the starting 2 toughness. Maybe just sub Wall of Runes for Witching Well against aggro? Can still be flickered for a scry 1.. Evaluation of sideboarding or how to approach different strategies is not my strong suit, but I'm learning. Against control, I imagine replacing Barrin and Shark with more direct payoffs would be appropriate, I'll be looking into that.
