Upgraded hydras will wipe out a surrounded defense of cannons. Not fully tho, even 2/2 they can knock out cannons. With a defiler or 2 with dark swarm then the cannons are really screwed. And against a zerg with lurks just have some ovies around ur hydras. They usually protect them. and if the ovies die bring in some more!
Dude lots of things can take out max hydras, like max gaurdians. Or lurkers, tanks, photon cannons if they build their entire base cannons. I go max hydras though because they own. Then I go MAX gaurdians. Forget air defence that leaves room for more gaurdians to do more damage. Maybe like 24 scourge.
A single high templar can kill 10 hydras in 1 storm if u mass hydras, because they cant pull them back fast enough if they attack the cannons. A mass cannon defence wont work tho, the zerg can just make a lot of zerglings and destroy the cannons.
triple post lol but turn them into gaurdians they will mess up cannons like little bitches I always do that to newbs who know they play vs zerg and still build lots of cannons. You dont build cannons against zerg.