When you bring your little lantern pet, or anything that gives off charge, into the area of a seeker, the seeker will double in damage and speed and will aggro towards you until the source of charge has depleted. Oh and they spawn in big numbers, so run for your life.
They they get a 50% incoming damage reduction whenever they’re affected by the light from a light pet or light plant. So toggle those puppies to off to kill seekers quick! Just be ready to taco them back on if any nameless spawn.