Aim for the Head Achievement in Halo: The Master Chief Collection

This Multiplayer medal is represented by a “targeted” skull and only earned via a precision weapon in Halo: Combat Evolved, Halo 2 Classic, Halo 2: Anniversary, and Halo 4. It is awarded to players upon killing an opponent by shooting them in the head. Though this achievement can obviously be done in regular matchmaking (best done in SWAT) as progress will be obtained naturally, this can also be boosted with at least three players in Forge. To do that, be sure to follow the steps below:

• Enter Halo 2’s Forge through the Main Menu’s Multiplayer tab and set the map to Nebula
• Have all three players meet up on the single platform
• Enter Editor Mode and move the white respawn point to the edge of this platform
• One player will act as the “Dummy” player and kill themselves by jumping off the platform
• Player “A” will stand to “Dummy’s” side and melee him as soon as he spawns
• Player “B” will then perform a headshot on “Dummy,” causing Dummy to fall off the platform
• This will give Player “A” an Assist medal for the "Nice Work Dawg!" achievement and Player “B” will receive a Headshot medal
• ”Dummy” will respawn at the edge right away
• Repeat this process for as long as necessary

As a note, make sure to tweak the gameplay options in the Forge lobby under “Options” before loading up the match. Under “Respawn Time,” change it to “Instant” and then under “Player Traits – Weapons and Damage,” change the primary weapon to a Beam Rifle and give it a bottomless clip. This will allow the “Dummy” player to respawn as soon as they are killed, giving Players “A” and “B” nearly 250 headshots/assists every seven minutes. Once you have obtained 2,500 Headshot medals, this achievement will unlock.