Best One Mana Spells in Ixalan Standard - BLUE

[DelverMage]

Blue does not have a plethora of creatures on the one mana list, but is does have some good spell choices.  Often though, Blue tends to have some of the BEST cards at these two cost levels, and I think Ixalan is no exception.

Creatures
Siren Stormtamer – A Blue Pirate that also is a 1/1 evasive flyer for one mana.  Still a strong choice, but add in the ability to spend a point of blue mana and sacrifice it to counter a spell or ability targeting you or one of your creatures and it becomes easy to make this a 4 of in any deck sporting blue.  If you have other cheap blue instants that you are holding blue mana up for, having this in play gives you another strong option to disrupt your opponents’ plan.  Don’t forget that your Stormtamer has this ability, it is easy to do.  Just remember, there is also a good chance your opponent will forget about it too.  (Until it causes them to lose a game…..)

Slither Blade - This blue naga rogue is only slightly better than a stock one mana creature at a 1/2.  This Naga is sneaky and should be a ninja as it is unblockable.  Perfect target for some combat tricks, auras, or some equipment, like Dousing Dagger, and you have hits on players or planeswalkers not named Gideon of the Trials.

Spells
Dive Down – Here is the Blue answer to targeted removal.  Certainly more defensive then Blossoming Defense, but both equally useful for protecting your creature.

Opt – Scry 1 and then Draw a Card.  Like what you see, then put it in your hand, if not, put it on the bottom of your library and keep the next card.  Opt is reprinted from the Invasion set way back when.  This is a go to card in Blue, and again is often an automatic 4 of in decks that have blue.  This is one of the best one mana cards in Standard currently, at least top 5.

Spell Pierce – Counter target NON-CREATURE spell, unless they pay 2 mana.  Vehicles and other artifacts are NOT creatures!  For one mana this card is excellent against both Black and Green on turns 1-3 or so (Fatal Push, Attune with Aether).  After that, it is more of an opportunity card that may well just end up taking space in your hand.  Don’t forget that often, it is worth using a Spell Pierce even when they can pay it, if it means they are now tapped out.  This provides you a window to act, with little to no chance of interruption from your opponent.

Unsummon – This reprint is as simple as they come.  Return target creature to its owners hand.  I have been abusing this card from the beginning (of Magic) and this card is effective, as long as your opponent is playing with creatures.  There are so many tricks you can play with Unsummon.  Disrupting their attack, foiling their combat tricks, rescuing your own creatures from targeted removal, just limited by your imagination, a legal target, and one blue mana.
 
Sideboard
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[DelverMage]

I have edited the original thread to add in Slither Blade. 

I have a formulary in place now to help be more consistent and definitive in my ranking of these cards and the extra toughness squeaks Slitherblade onto the chart.