The key thing to think about when determining whether a Hexproof creature is affected by a spell is whether that spell is targeting it
Mila, Crafty Companion / Lukka, Wayward Bonder Like the Magic Origins flipwalkers, Mila, Crafty Companions another planeswalker thats cheating on the rules a bit
Legendary Planeswalker Koth
Counterspell - unconditional counterspell Muddle the Mixture - poor counterspell but can tutor for both pieces of Iso-Rev combo or Cyclonic Rift Remand - excellent counterspell for fighting other blue mages that have lots of counterspells as you can remand your own spell to 2-for-1 the opponent
As far as expensive cards go, there isnt a ton to talk about
These decks also need lots of mana, so playing cards that interrupt an opposing ramp engine can also slow the extra turns player down enough for the table to beat them down before they take over