Klaxon and Obliterate are creep staples, Grimwar and Crescendo are swarm staples (I prefer Grimwar). Also Vorpal Reaver is a personal favorite of mine that fits into a large variety of decks.
Mindlathe and Nether Summoning are more like tech cards. 2x is fine for the right deck, but I’d go either for the creep or swarm cards above first depending on what you like to play.