Ponder, Brainstorm and Gush are our cantrips. I find that these work best with Delver and I also just like using them. I remember a time before Modern, I used these spells a ton!
Counterspell, an old classic. The card that literally got me into the game as a child. "I can play a card that just tells my foes no? I NEED to play this game!" - 10-year-old DMFF.
Daze is a really effective "free" counterspell that can really save our butts!
Snap is a super nifty card. It's great for temporary removal in a pinch. This also could be used to return a Spellstutter Sprite to our hand as well as granting us the mana to play it!
Lightning Bolt is always a classic and amazing card. 3 damage to any target is always good for one mana.
I am utilizing Snow Lands in this deck for Skred. This makes removing larger creatures a ton easier.
Last, but certainly not least, Kaervek's Torch is an old friend I used to play in my second deck ever. It's a nice wincon and has a counter-deterrent attached to it! This alone can put me at an advantage in mirror matches.