Dying Wish abyss tends to wreck Vaath. Chakram is an abyss staple and is brutal on Vaath because it puts things out of plasma range and makes rebuke dangerous. Any deck can tech 4/5s, dispel, and similar to give him a real hard time.
Vaath is one of the easiest decks to tech against without hurting your other matchups and or just playing around their stuff goes along way. AKA do not over extend into a wipe. Diagonal placement to avoid frenzy. Not backing off early on, waiting till drogon lethals are a possibility to give up mid control that way you have time to back off later on. Always keep finality in mind so do not rely on things that are 8 plus mana in that matchup. Both in terms of tech and counterplay Vaath has some of the most.
Basically my entire IV thread was built to beat Vaath during the 3 mana rebuke/7 mana finality days and I absolutely stomped him because it was everywhere and easy to tech against. (Thread did get reworked a ton post nerf though.)
Kron by its self dodges magmars entire kit, two bodies the smaller one protecting Kron from nat select, 4/5 avoiding rebuke/slasher/kantor/lance/Plasma. Lightbender dispels the stun and atk buff on finality or just Vaath at any point and is also an excellent meta choice to dispel tiles/walls.
Dying wish in general is good vs magmar. Abyss has lots of options in that regard and or artifacts. Vet has Aymara/Mirage/Fault/Kha/Kanopic/Swarm King. In Vanar Luminous/MWisp are pretty hard on em while cloud caller and moose dodge all the removal. Lyonar has Titan, Afterblaze, Oaken Heart, Grandmaster, Argeon atk manipulation, Vitirol, and careful use of Aurora. Songhai has artifacts a plenty, Ox can tech a lot of neutral removal resistant bodies, and nonsense OTKs work although finality is hard on them.
More neutral options aside from Lightbender/Kron,: Redsteel Minos, Sell Soul, Dioltas, Owlbeast (Meaning arcanyst across the board), Blue Conjuerer, Dancing Blades. And those are just the good ones. Stuff like EMP and similar is not perfect as it eats it to rebuke but is still a great powerhouse that makes most decks better and dispels.