NEVER ever get your tamed giga’s health to be under 50% or lower, it will activate RAGE mode. Rage mode is an aggressive stance that eats on EVERYTHING including you and your tames even if it’s tamed. Becareful of using the giga against a powerful dino or jumping of a cliff while riding a giga, entering rage mode while riding a giga will kick you off it’s saddle and eat you. Rage mode typically lasts for 20 seconds, however rage mode will buff the giga into a deadly machine! Rage mode buff will make your giga’s damage to 2x the damage. You might notice it’s glowing eyes when you suspect it to be in rage mode. I may be suggesting you removing your best weaponry and Armor to your base when your about to ride your giga anytime if you want for a risky stunt/adventure. After its rage mode finished it’s timer, it will go back to normal and it’s still tamed if your worried.
(I've only tested this out on mobile, idk if it works on pc!) If your Giga rages, you can end the rage by doing this: Put your device to sleep, and join into ark again. The giga should be calm again! I once fell off a ledge with my Giga, Giggy, and she raged. I reset my ipad to calm down, and when i came back, Giggy was calm and mountable again! Giggy is fine now btw. I had been planning to turn invulnrability on, but i looked around and Giggy was calm. I hope this helped you and your raging Giga!
I triple dog dare you to tame 2 EXTREMELY high level gigas (When I mean extreme I mean around 200-250, or above) and breed them you'll come out with a freakin' bulldozer that can go toe to toe with the dragon boss, ALONE.