It's all about this
4 pieces: Each time you use your Kill Command ability, your attacks ignore 600 of your victim's armor for 15sec.
I made two different chars on Cheekys DPS Spreadsheet, one with 4x Beast Lord+Kara/Mag/Gruul and one with just Kara/Mag/Gruul gear.
Numbers are with a 25 raid comp, may or may not be correct. It's just to compare both setups.
BEST IN SLOT WITH REGULAR KARA/MAG/GRUUL GEAR
https://imgur.com/ydwcicQ
Total DPS: 1904,94
Head: Demon Stalker Greathelm
Neck: Choker of Vile Intent
Shoulders: Bladed Shoulderpads of the Merciless
Back: Vengeance Wrap
Chest: Chestguard of the Conniver
Wrist: Shard-bound Bracers
Hands: Gloves of Dexterous Manipulation
Waist: Gronn-Stitched Girdle
Legs: Skulker's Greaves
Feet: Edgewalker Longboots
Ring: Ring of a Thousand Marks
Ring: Ring of the Recalcitrant
Trinket: Dragonspine Trophy
Trinket: Darkmoon Card: Crusade
2H Weapon Legacy
1H Weapon: Guile of Khoraazi
1H Weapon: Blade of the Unrequited
Ranged: Wolfslayer Sniper Rifle
Quiver: Netherscale Ammo Pouch
Ammo: Mysterious Shell
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BEST IN SLOT WITH BEAST LORD 4-PART + KARA/MAG/GRUUL
https://imgur.com/tb0OXuK
Total DPS: 1903.67
Head: Beast Lord Helm
Neck: Choker of Vile Intent
Shoulders: Beast Lord Mantle
Back: Drape of the Dark Reavers
Chest: Beast Lord Cuirass
Wrist: Shard-bound Bracers
Hands: Beast Lord Handguards
Waist: Gronn-Stitched Girdle
Legs: Skulker's Greaves
Feet: Edgewalker Longboots
Ring: Ring of a Thousand Marks
Ring: Garona's Signet Ring
Trinket: Dragonspine Trophy
Trinket: Darkmoon Card: Crusade
2H Weapon Legacy
1H Weapon: Guile of Khoraazi
1H Weapon: Blade of the Unrequited
Ranged: Wolfslayer Sniper Rifle
Quiver: Netherscale Ammo Pouch
Ammo: Mysterious Shell
As you see, the Beast Lord can compete with T4-level leather gear, it is only 1 dps apart.
Don't be ashamed to wear it "just because it's blue" or it "lowers my gearscore".
Please spread the word and check it yourself.