I did this trophy offline using the following loadout:
- Blasted Before Breakfast (Barb's Easy Blaster with Will'O path advanced upgrade) gun, somewhere around level 4 or 5 with 1200-1400 damage
- Ea's Knife at around 600 damage
- Defense: Peltatum/Attack: Peltatum and normal Attack/Elemental augmentations
- Binding Thorn fully upgraded
- Ammo Packs (optional)
- Elfriede at Lvl. 8, Beatrice at Lvl. 7, and Uwe at Lvl. 7
Go to operation XX7-5 Ghost Glow: Liquidation once you've got the proper equipment to face the Peltatum Abductor.
The first thing you need to do is drop its shield. Thorn up to the diamond-shaped plates on the Peltatum's front and sever them. Gunfire from your allies should slightly speed this up. If the chains are hitting you with their projectiles, don't worry about it too much. You may get knocked down, but your teammates will almost certainly revive you before you die, so it won't matter. Once those plates are off, the Peltatum is shieldless, and you should thorn up to the right of its eye (your right, not its right).
Once up here and latched on to the side of its eye, equip your Barb's Easy Blaster (or whatever variant you have at the needed damage) and start firing at the box directly behind the eye (not the boxes you can sever that release the chains). You know you're shooting the right thing if you get red flashes on the spot you're shooting at.
The trick here is that your Barb will kill the Peltatum before it ever has a chance to release the chains. Just unload clip after clip into the spot behind the eye until you run out of ammo, then use your ammo packs or get some ammo from the arena's boxes before returning to your spot and blasting the Peltatum some more. While you're down here, feel free to stun the abductor with your charged thorn and give yourself more time to blast it before the chains are released.
If you ever see the Peltatum's back (with all the chains) make a tight box, jump off and let it fall. You won't receive any damage this way, and you can swiftly latch back on and keep firing. If it becomes immobilized and you think it's about to explode before rising back up, just keep firing, don't jump off. Sometimes the Peltatum won't explode and you'll be fine, but otherwise, you need to keep doing damage. There's a good chance you'll still get hit by the explosion if you try to jump off and run away, so don't even bother with it.
If the chains get released when the Peltatum's lifebar is low, KEEP FIRING. Get back in your position on the side of the eye and shoot until a chain knocks you off or until you run out of ammo. There's a great chance that the lifebar is low enough to where you can kill it before the chains start linking hit after hit on you, which would basically spell death.
With this method, you can speedrun the Peltatum and kill it in 5 minutes or less without dying, gaining you the gold trophy.