Bounce something that got through your counter shield so you can counter it
One Mana Hosers : Cards with a converted mana cost of 1 that have unusual hosing effects, most more useful outside of Standard
Mirror Pool
If a mid-range approach isn't your speed, you can always take a more control approach with Kenrith, stocking up on counter spells and some hatebears effects to control the board
This does weaken the draw-go aspect of the game, which Ive been compensating with by adding a fourth Counterbalance, while not playing overly reactive cards like Spell Pierce in this particular list, which is also due to the fact that a list with such a multitude of cantrips isnt able to play as many individual cards as other lists can, with the upside of finding those, mostly superior, cards with a higher reliability
I spent the majority of my first 10 hours in Arena playing against Sparky, trying out each of the decks in turn and raising my account mastery level to unlock more cards