Suggestion 1: King of the Hill
Info: It's like the normal Lockdown thing but with 1 point, that takes double the time or something to cap, and hold it for 3 minutes. (Or set it up in points)
Point is in the middle.

Suggestion 2: Deathmatch
Info: You get points for kills, however, it's up to you if classes are allowed or not in that. (I suggest not since it's not the normal LD and people target other people)

Suggestion 3: Horde mode
This is a 3-sided thing, while you fight over the points, sudden monsters appear to attack (I suggest Mecha Knights or NPC class knights, or even Ghostmanes!)

Suggestion 4: Last Man Standing
Free-for-All mode, you start with like uh.. 60 HP or 50, and you fight against many others (classes not reccomended for this)

Suggestion 5: Team Swap
Kill someone to put said person in your team.
Whatever team gets empty, has the opposite one win.

Suggestion 6: Monster-Lockdown
You choose a monster to play as. (Reccomended: Mecha Knight = Striker/Ghostmane = Recon/Trojan = Guardian)

Suggestion 7: Zombie Mode
Play as any Zombie Dreadnaught you want, cursed not allowed, but Slag Guards are

Suggestion 8: Machine Defense
2 big Battlepods that don't have shield up are on each team side, and their opposite has to destroy that Battlepod to win, either has high HP based on total of players for each team. (you decide wether or not the battlepods have bullet chains)

That's all I got in mind.