Although Spirits is usually Bant or white-blue, thanks to some spicy new ghosts in Core Set 2021, now we can run mono-blue and bring the price tag for the deck down a ton. Check these spooky dudes out:

So the plan here is simple. Play some fast evasive creatures, slap a Curious Obsession on them, protect them with Unsubstantiate and Rattlechains, PROFIT. Check it out in action below.

Magic: The Gathering TCG Deck - Budget Mono Blue Spirits (Pioneer) by Meryn

'Budget Mono Blue Spirits (Pioneer)' - constructed deck list and prices for the Magic: The Gathering Trading Card Game from TCGplayer Infinite!

Created By: Meryn

Event:

Rank:

Freeform

Market Price: $38.15

Cards

Supreme Phantom

Color Identity:U

Market Price: $0.96

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/169230_200w.jpg

Flying
Other Spirits you control get +1/+1.

Buy This Card! https://shop.tcgplayer.com/magic/core-set-2019/supreme-phantom

Curious Obsession

Color Identity:U

Market Price: $0.95

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/216308_200w.jpg

Enchant creature
Enchanted creature gets +1/+1 and has "Whenever this creature deals combat damage to a player, you may draw a card."
At the beginning of your end step, if you didn't attack with a creature this turn, sacrifice Curious Obsession.

Buy This Card! https://shop.tcgplayer.com/magic/jumpstart/curious-obsession

Island

Color Identity:U

Market Price: $0.14

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/222819_200w.jpg

({T}: Add {U}.)

Buy This Card! https://shop.tcgplayer.com/magic/zendikar-rising/island

Nebelgast Herald

Color Identity:U

Market Price: $0.30

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/216535_200w.jpg

Flash (You may cast this spell any time you could cast an instant.)
Flying
Whenever Nebelgast Herald or another Spirit enters the battlefield under your control, tap target creature an opponent controls.

Buy This Card! https://shop.tcgplayer.com/magic/jumpstart/nebelgast-herald

Essence Capture

Color Identity:U

Market Price: $0.18

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/183208_200w.jpg

Counter target creature spell. Put a +1/+1 counter on up to one target creature you control.

Buy This Card! https://shop.tcgplayer.com/magic/ravnica-allegiance/essence-capture

Mausoleum Wanderer

Color Identity:U

Market Price: $2.47

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/120513_200w.jpg

Flying
Whenever another Spirit enters the battlefield under your control, Mausoleum Wanderer gets +1/+1 until end of turn.
Sacrifice Mausoleum Wanderer: Counter target instant or sorcery spell unless its controller pays {X}, where X is Mausoleum Wanderer's power.

Buy This Card! https://shop.tcgplayer.com/magic/eldritch-moon/mausoleum-wanderer

Shacklegeist

Color Identity:U

Market Price: $0.19

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/215701_200w.jpg

Flying
Shacklegeist can block only creatures with flying.
Tap two untapped Spirits you control: Tap target creature you don't control.

Buy This Card! https://shop.tcgplayer.com/magic/core-set-2021/shacklegeist

Castle Vantress

Color Identity:U

Market Price: $0.82

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/199284_200w.jpg

Castle Vantress enters the battlefield tapped unless you control an Island.
{T}: Add {U}.
{2}{U}{U}, {T}: Scry 2.

Buy This Card! https://shop.tcgplayer.com/magic/throne-of-eldraine/castle-vantress

Dive Down

Color Identity:U

Market Price: $0.13

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/145743_200w.jpg

Target creature you control gets +0/+3 and gains hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.)

Buy This Card! https://shop.tcgplayer.com/magic/ixalan/dive-down

Rattlechains

Color Identity:U

Market Price: $0.55

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/216536_200w.jpg

Flash
Flying
When Rattlechains enters the battlefield, target Spirit gains hexproof until end of turn.
You may cast Spirit spells as though they had flash.

Buy This Card! https://shop.tcgplayer.com/magic/jumpstart/rattlechains

Annul

Color Identity:U

Market Price: $0.11

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/71315_200w.jpg

Counter target artifact or enchantment spell.

Buy This Card! https://shop.tcgplayer.com/magic/theros/annul

Mystical Dispute

Color Identity:U

Market Price: $1.20

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/198683_200w.jpg

This spell costs {2} less to cast if it targets a blue spell.
Counter target spell unless its controller pays {3}.

Buy This Card! https://shop.tcgplayer.com/magic/throne-of-eldraine/mystical-dispute

Spectral Sailor

Color Identity:U

Market Price: $0.26

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/216411_200w.jpg

Flash (You may cast this spell any time you could cast an instant.)
Flying
{3}{U}: Draw a card.

Buy This Card! https://shop.tcgplayer.com/magic/jumpstart/spectral-sailor

Ghostly Pilferer

Color Identity:U

Market Price: $0.47

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/215728_200w.jpg

Whenever Ghostly Pilferer becomes untapped, you may pay {2}. If you do, draw a card.
Whenever an opponent casts a spell from anywhere other than their hand, draw a card.
Discard a card: Ghostly Pilferer can't be blocked this turn.

Buy This Card! https://shop.tcgplayer.com/magic/core-set-2021/ghostly-pilferer

Aether Gust

Color Identity:U

Market Price: $0.76

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/192535_200w.jpg

Choose target spell or permanent that's red or green. Its owner puts it on the top or bottom of their library.

Buy This Card! https://shop.tcgplayer.com/magic/core-set-2020/aether-gust

Unsubstantiate

Color Identity:U

Market Price: $0.08

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/215676_200w.jpg

Return target spell or creature to its owner's hand.

Buy This Card! https://shop.tcgplayer.com/magic/core-set-2021/unsubstantiate