Cliff Bleszinski, in a post Gears 3 release interview with Edge, has described how the development team designed the boss and teh subsequent battles to be more than just massive beats its takes a few minutes to kill.
According to Bleszinski, boss battles in the game are designed with three things in mind, and used the giant Corpser battle as an example.
"I can't take much credit for that battle outside of playing and giving feedback," he said. "That boss fight was snuck in by one of our developers – Rob McLaughlin – who's a bull-headed great programmer of ours. But I go back to the rule of threes with bosses, on average it's like you want three phases. You're fighting Bowser and the first phase is the exploratory phase and phase 2 it gets a little harder and it's a challenge and you have the prestige. But you have to that moment where now he's really mad, and one of the things I've seen from the reviews thus far is that we finally have boss fights that people feel are worthy of a game like this whereas a lot of them where kind of tacked in or disappointing in previous ones.
"Especially with the final boss battle in Gears 3 we wanted to make sure it felt like an ending that was worthy, and that it was something that you know, a large scary creature you had to take out that took more than a minute or two.
"I think the Lambent Beserker was one that we were really happy with, speaking of multiple phases. She initially just had the ability to leave the trail and the goo behind and could jump and I was like, let's back up, don't make her jump at the beginning, and then eventually she gets angry and then starts jumping more and then starts boxing you in, Tron light-cycle style. Then eventually she gets harder and harder and you take her out because you want that challenge, that torque that makes the palms sweaty.
"And if you don't have that the game gets boring and you just go and screw off on social media."
You can read the entire interview through here, but be warned: it contains massive spoilers, and because I had to read through it to find information for you, the story is now totally ruined for me.
Gears 3 was released on September 20 and has sold 3 million copies already.