Nix

Instant
Counter target spell if no mana was spent to play it.
Its probably the 2nd best 1 option for a 1 mana counter. Reb* being the best 1 mana counter. *- ok REB and Pyro are tied for 1st, but really its the same card!
This little number seems like a nice combination of mini-annul, and mini-Reb.
Vintage cards this counters:
0cost artifacts
>
Lotus> other moxen
> Chalice @ 0
> EE @ 0
> Tormod's Crypt
> ... anything that SenseiSensei brings in under helm
> ... Affinity creatures~
Pitch Magic/ACC
> Force of Will
> Misdirrection> Fire Blast~
> Pulverize~
Freebies:
> Massacre> Basiking Rootwalla~
> the new Futuresight "Pact" cards
Manaless Flashback
> Dread Return
> Cabal Therapy> Lava Dart~
Copies of Spells:
> good against a weak Empty... maybe for like storm 1 or 2.
> Twincast/Fork~
Suspend:
> Gargadon~
~ = not common but not irrelevant to Vintage.
Bold = probably 95% of the time this card is cast, it will hit something in bold.
.... Thats not a terrible list. Especially for a deck like Non-Red fish.