When the Darkspore invaded Infinity, they granted the mech-defense units called Blastopods a special mutation. That mutation allowed blastopods to metabolize numerous pollutants to become extremophilic killing machines. The slow moving Blastopods adapted themselves to shooting medium range homing projectiles at anything that stood against them. They can do so only while stationary.
Their missiles were practically impossible to evade and had a fairly long range, making them very hazardous in larger numbers. So the best way to deal with Blastopods would be utilizing quick attacks and fast heroes to kill them off before they've dealt too much damage. However, they should remain immobile in order to shoot, and they did not fire them very quickly, so ranged heroes such as Tempests could pick them off from a distance while taking relatively little damage.
Andromeda's Gamma variant would be very effective against Blastopds, because she could use her Repulsion Sphere squad to deflect their missiles back at them, and she could also slow-down their projectiles with her Time Bubble variant ability.
Wraith's Ghostform squad ability would also be helpful, because it would cause their missiles to simply pass-through the user, making these emeies completely harmless.