Most played cards in Mono Blue Control:

5 Decks
Riftwing Cloudskate
20 copies - 4 average
Vesuvan Shapeshifter
20 copies - 4 average
Desert
20 copies - 4 average
Serrated Arrows
20 copies - 4 average
Ancestral Vision
20 copies - 4 average
Cancel
20 copies - 4 average
Snapback
19 copies - 3.8 average
Teferi, Mage of Zhalfir
19 copies - 3.8 average
Dismal Failure
18 copies - 3.6 average
Aeon Chronicler
15 copies - 3 average
Trickbind
12 copies - 2.4 average
Willbender
12 copies - 2.4 average
Brine Elemental
11 copies - 2.2 average
Urza's Factory
10 copies - 2 average
Fathom Seer
8 copies - 1.6 average
8 copies - 1.6 average
Draining Whelk
5 copies - 1 average
Ovinize
4 copies - 0.8 average
Voidmage Prodigy
4 copies - 0.8 average
Psionic Blast
4 copies - 0.8 average