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ION Loaders are primarily defensive units among Hyperion's robot ranks, and aside from being shock damage specialists, they have an ability to generate a shield bubble that is impervious to enemy bullets.
ION Loaders carry twin Tesla coils on their shoulders and at the ends of their arms. The ION Loader can charge them up by spinning its upper body and emit a bubble shield that deflects incoming bullets and grenades, but allows friendly bullets and units to pass through unimpeded. The shield does not block movement, but passing within its boundary causes the ION loader to fire a stream of lightning from its pack that can quickly sap shields and health. When its shield is inactive, it shoots a stream of powerful electric bolts from its right arm. When the shield is up, nearby loaders (excluding EXP Loaders and other ION Loaders) will make an attempt to get under it. If the shielded ION Loader is knocked back or if it takes significant damage, the shield will be disabled.
Splash damage will pass through the shield bubble. Singularity grenades detonating near the shield will cause the ION Loader to stumble, thereby disrupting the shield, although any grenade with a large radius may also be useful if it can damage the ION Loader from the edge of the shield bubble. Longbow grenades can also be useful in positioning a grenade inside the shield bubble before the ION Loader has spun up to full generating speed, and in this manner Corrosive Cloud or Bouncing Betty grenades can prove deadly to the ION Loader and other loaders marching into the shield radius. In the case of a "Homing" grenade, the grenade will attempt to penetrate the shield dome, but ultimately just keep bouncing away. A child munition of a Homing Bouncy Betty grenade detonating at the periphery of the shield may still bounce into the shielded area however. It is also possible for an attacker to rush inside the shield with a high-damage weapon and disrupt the shield before taking significant damage.
It is generally impossible to highlight and therefore Phaselock a shielded ION Loader. Using Res on a teammate inside the shield has similar disadvantages. Zer0's Deception ability does not prevent him from taking damage if he steps inside the shield. The Converge, Execute, Nuke and Fistful of Hurt skills cause knockback which may disrupt an active ION Loader. However, it may be preferable in some circumstances to simply retreat to cover and wait for the shield to expire. If Axton's Sentry is equipped with the Longbow and Nuke upgrades, he can simply throw a turret next to the ION Loader's shield. The blast radius is more than enough to stumble and damage the ION Loader (and any loaders inside).
The limbs of ION Loaders are reinforced, preventing them from being shot off, and leaving the optic sensor as the only option for critical hits. In addition they are also resistant to shock.