Four's a Party
Down 4 enemies in one round 
Note: You can’t get any trophies in any game modes labeled “(Bots)”.

The easiest way to get this down is in “Strikeout”. Just play aggressively and you should easily get 4 downs in a single round. Dima is a good Rogue to earn this with as he is entirely offensive and has pretty straightforward abilities, gadgets and perks. Also, his primary gun, the KA30, has very low recoil; however, feel free to use whichever Rogue you are comfortable with.
Zeal
Down an enemy with a melee weapon 
Note: You can’t get any trophies in any game modes labeled “(Bots)”.

Every Rogue can purchase a melee weapon for $4,000. The easiest way to get this is during the first round of a “Demolition” game. Your initial purchase should be a melee weapon, pretty much everyone else in the game will only have pistols in the first round. Rush an enemy and begin to melee them until they go down (3-4 hits).