Why Gearbox Created a Borderlands 2 Boss So Tough It's Nearly Invincible

Eurogamer is offering a detailed feature on Borderlands 2's endgame content, with talk of "raid bosses", an additional difficulty mode which is not meant to be for the faint of heart, and more. Here's an excerpt:
One end-game raid boss, though, won't be enough to keep the hardcore happy. Varnell mentions "game changers". Each character class has one: a unique ability deep down at the end of a skill tree, only available at level 50 and designed to, as the name suggests, change the way you play.

Take Axton, Borderlands 2's soldier, for example. His base skill sees him deploy the Longbow Turret. But progress all the way down his skill tree and you'll unlock the Nuclear Detonation ability, which triggers every time you deploy the turret. It looks as over-the-top as it sounds, complete with a modest mushroom cloud effect. Combine this with the Longbow skill, which teleports your turret to wherever your crosshairs are aiming, and you have a pinpoint-precision nuke at your disposal. Combine all that with the skill that lets you pick up the turret after it's been thrown (which reduces the cooldown on your nuke), and you can get into a faster, devastating loop of throw, nuke, pick-up, throw, nuke, pick-up. "It changes up the dynamic of the soldier quite a bit from just a turret shoot type of class," Varnell says.

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Powerful skills are nothing without powerful enemies to use them against, of course. While Borderlands 2's normal difficulty will present a decent challenge to players, it's more about teaching the player how the character classes work, how the enemies work and how the guns work in a fun 40-odd hour blast 'em up. It's not until you beat Borderlands 2 on normal that you'll pit your skills against a real test.

Borderlands 2's second play-through is called True Vault Hunter Mode. Like the second play-through on Borderlands, TVHM is harder with tougher enemies. But where the first game simply tasked the player to increase their hit points and do more damage with better guns against enemies with more hit points and better guns, a second play through of Borderlands 2 requires the player to think. The AI works differently using unique behaviours. More enemies use shields. More wear armour. More are Badass class. There are enemies that only appear in TVHM. To defeat them you'll have to put those top-tier abilities to good use. And in co-op, which automatically scales up the challenge depending on how many are in your party, understanding how different classes work together is essential.

Eurogamer is also offering a short feature on the Mechromancer DLC class, which will apparently include a "Best Friend Mode" skill tree that simplifies the gameplay for co-op partners that are not particularly good or experienced with videogames:
"The design team was looking at the concept art and thought, you know what, this is actually the cutest character we've ever had. I want to make, for the lack of a better term, the girlfriend skill tree. This is, I love Borderlands and I want to share it with someone, but they suck at first-person shooters. Can we make a skill tree that actually allows them to understand the game and to play the game? That's what our attempt with the Best Friends Forever skill tree is."

One of the first skills available in the BFF tree is called Close Enough. This means your bullets that hit walls or other objects, that is, miss their target, have a chance to ricochet off towards the enemy. "Can't aim? That's not a problem," Hemingway said.

In a gameplay demo, Gearbox showed this skill in action. At points, after taking damage against bandits, the Mechromancer was able to hide behind cover waiting for shields to recharge. From there, she could safely shoot in the general direction of the enemy, with bullets magically hitting targets.