The Savage Hunters are quick agile warriors that shoot deadly poisonous darts.
Savage Hunters are less resilient than Savage Warriors, but they shoot poisonous darts, which can quickly carve a hole in your ground defenses.
Always keep your hero away from Savage Hunter to avoid heavy wounds from their darts, unless you are using Grawl, who is armored and immune to poison.
Due to their numerous appearance, it is hard to micromanage soldiers away, so you should recruit fast-respawn Assassins to inflict some damage before dying, or call Knights Templar with investment on Toughness to survive the poison.
Necromancer's skeletal minions, including the Death Rider, cannot be poisoned. Strategically place him where he can reach a healthy supply of corpses, and support him with two or more Battle Mecha to avoid Tricksters stealing the bodies, you should be able to resist Savage Hunters entirely.
They cluster together when attacking, so therefore, any kind of level 4 Artillery is a hard counter to these enemies, if placed where they grouped to shoot at soldiers.
Consider grouping soldiers at the back, forcing the Savage Hunters to enter the range of towers.