Misty cards are usually a safe bet
Playability Cards that are must-haves in tournament decks can become expensive, even if theyre common
C Common Vanadis of the Nordic Ascendant X DARK Level 4 [ FairyTunerEffect ] ATK 1200 DEF 400 For a Synchro Summon, you can substitute this card for any 1 "Nordic" Tuner
If your opponent activates a Spell Card or effect on the field, you can negate it and make Jellyfish gain 600 ATK
In a deck that can go wide on the board, as Knights certainly can, this ability is incredibly dangerous, and can easily finish an opponent off in conjunction with other board-buff effects such as History of Benalia
World Championship 2015, @hasekyon1218 4th, Chase Robert Cunningham (USA) [Artifact Tellarknight] Source: Yu-Gi-Oh