Be creative here there are no wrong ideas.
I would like the Spartan laser to be a weapon personally, just called something different "Charge Rifle" was a name I had in mind
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The Zorg ZF-1 with replay!! or Solar flame thrower, pretty self-explanatory Void black hole that sucks the enemy into it and kills them or in crucible teleports players to other areas of the map with no shield when they land. Arc throwing disks that bounce of walls or objects killing anything it touches, last 5 secs