>>27
Every one of those spiderlings procs counterhelix. Counterhelix has a 20% chance to proc, she sent… What, 15 or so broodlings at him? Not even simultaneously, so they triggered it in waves.
Even without taking PRNG into account, that's a shitload of counterhelix procs. Mirana and brood also both used abilities (leap/insatiable hunger) that increase attack speed, making it proc even more. 100 damage per helix at level 1, 205 at level 4. No shit they got chewed through.
The most embarrassing thing is that mirana's attack range is more than double counterhelix's radius (600 vs 275). She straight up committed suicide there, while killing broodmother at the same time.
TL;DR: Dumbasses get rekt by not understanding the heroes' abilities. Referring both to you and the people in the gif.