Metal Gear Survive: How To Fight Two Legendary End-Game Bosses

Once you’re done with the campaign, there’s still more left to do in Metal Gear Survive — you can unlock subclasses for one. Even better, you can fight legendary optional end-game bosses that seem impossible to beat at first. These aren’t just recreations of old enemies. These are special creatures with totally new attacks and abilities.

There are two of these big, bad bosses — Big Mouth and Frostbite. Big Mouth is a T-Rex-like abomination with machine-guns and a huge set of chompers. It looks like a particularly deadly Monster Hunter: World monster and fighting it might take just as long. Frostbite is even more bizarre. It’s a jellyfish / octopus hybrid that can fly in the air, looking 100% alien. They’ll both drop awesome gear, so if you’re sticking around for the long run, here’s how to fight them.

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How To Fight Two Legendary End-Game Bosses

After completing the first Base Defense, you’ll also unlock another special mission type – ‘Powerful Creature Detected’ – these are special end-game boss monsters you can fight for huge rewards. They’re also incredibly tough, so I don’t recommend fighting them until you’ve unlock the new character classes and put points into them.

NOTE: Defeating boss monsters will net you Orange loot boxes.


Big Mouth

The first boss, Big Mouth, is Level 43 – it’s a giant T-Rex monster with a huge mouth and a side-mounted minigun that can wipe you out very quickly without the right equipment. Not even grenades can put a dent in this thing. Post-game bosses are a true challenge, and you’ll want to complete more Base Defenses and other side-quests to increase your level. Co-op scavenger missions are very important for collecting Kuban energy.

  • To make this incredibly tough boss easier, use the Scout’s invisibility ability. Hide behind the fence entrance into the ruins arena — the Big Mouth can’t follow you.

Bring a powerful shotgun, heavy arrows, C4, turrets, grenades and molotovs. When your invisibility drains, run and hide. Wait for it to come back, then rinse and repeat. That’s the easiest path to a Big Mouth victory.


The second boss, Frostbite, is Level 50 and only appears after defeating Big Mouth. Instead of a T-Rex, Frostbite is a strange flying octopus-like monster that’s actually quite a bit easier than the Big Mouth monster. Once again, you can use the Scout invisibility to clear the arena of wanderers — then target the weakpoint with a Sniper Rifle.

  • When Frostbite glows orange, shoot the spot with a powerful Sniper Rifle. Hit that spot twice to stagger Frostbite, knocking it onto the ground and stunning it.

While Frostbite is stunned, rush close and unload your shotgun into the glowing orange weak point. Keep shooting until it recovers — rinse and repeat to bring Frostbite down for good.

Got your own legendary boss tips? Still need some help? Let us know in the comments!