Shredder Maniac

The Mechashredder 5000 is granted only if you chose the Lumber Yard (not the Sparring Arena) during the quest We Need An Outpost at your base in Highpass, Gorgrond. If you chose the Sparring Arena, you can pay 5,000 gold to the goblin woman standing in front of the arena in Beastwatch to switch to the Lumber Yard. If you are playing Horde, she is right there at Beastwatch. Your Highpass outpost choice is otherwise permanent and cannot be changed through any other means.

If you already permanently chose the Sparring Arena and cannot or do not want to pay to switch, form a party with a player who has the Mechashredder 5000. That player cuts the Hardened Thornvines, and anyone in the group can then loot them to progress the achievement.

Travel to the following locations in Gorgrond and loot the Hardened Thornvines after they are cut. You need at least 12 looted to complete the achievement. Head to at 47.23, 51.83, at 42.92, 43.48, at 47.53, 43.60, at 49.04, 48.47, at 53.30, 46.77, at 50.18, 53.79 inside cave #2 (enter at 49.04, 53.5), at 42.35, 54.78, at 39.31, 56.25, at 56.76, 57.23, at 63.30, 57.20, at 51.77, 61.51, at 40.92, 67.32, at 47.02, 69.07, at 51.79, 69.10, at 51.66, 72.22, at 60.50, 72.73, at 47.61, 76.81, at 41.12, 77.28, at 51.39, 77.59 (cave entrance #1), at 52.98, 79.07 inside cave #1, at 49.59, 78.86, at 41.96, 81.6, at 45.34, 81.98, at 45.97, 93.6, and at 45.79, 89.30.