Brütal Legend

I got this playing a custom match vs Most Gentle AI Drowning Doom on Feeding Area.

First, capture every geyser on the map. This includes the one near the enemy stage, to slow the AI down while you prepare. Upgrade your stage all the way while you repeatedly kill Ophelia and anything she summons, then purchase a Bleeding Death.

You may also want to set up some squads guarding the other geysers. I found Warfathers and Skull Rakers work well for this.

Now stand/fly just outside the enemy stage area and play the waiting game. Let Ophelia summon Grave Diggers and wreck/replace your merch booth right next to her stage. If she summons a Bride or Frightwig, kill it, then fly out of there. She should eventually have 3 squads of Grave Diggers, making 18 enemies. (If she sends them into action before this, this is what your guard squads are for.) Once you see the 3rd Grave Digger squad emerge from the stage, play the Launch of Death solo to send in your Bleeding Death. While your monstrosity emerges, run in and get the enemies' attention and draw them back towards your killing machine. After pounding the Grave Diggers into the ground, the Bleeding Death should go after the stage. Ophelia should summon some new Grave Diggers during the rampage, which will make up the other 2 you need for the achevement.

This technique also works well for Dollpocalypse, Ringleader, and Euthanasia.

Play a custom match with your friend. Play as Tainted Coil and have him play as Ironheade. Tell him to spawn 20 headbangers (there are 4 headbangers to 1 squad so tell him to spawn 5 squads). While he is doing that, you go and capture some fan geysers to get some resources. You are going to eventually upgrade you stage all the way. When you do, select the Bleeding Death unit using the right bumper. This will unlock a special guitar solo that summons the unit. Run over to your friends stage and tell him to make a mosh pit with all of his headbangers. When he does, play the Bleeding Death guitar solo near his stage. A giant cage will fall from the sky and a Bleeding Death will come out of it, slaughtering all the headbangers. You can't control the Bleeding Death but he is powerful enough to kill all the headbangers in a matter of seconds.

This can be done using the tainted coil in mutiplayer, first upgrade to the megastage. press LB then summon the bleeding death by pressing RT to activate the solo.

A capsule will drop from the sky unleashing a monster that cant be controlled.Just make sure to summon near enemies so it attackes them ,as you only have a limited time to get the kills.

Can be boosted with another player in a custom match

An easy solution is to play against the Drowning Doom on the Pleasure Gardens map (AI Practice, with Most Gentle difficulty.)

Simply capture each fan geyser, upgrading your stage and deploying more troops as you wish. Then, finally, when you have enough fans, purchase the Bleeding Death, and then as you wait for it to be ready for action, send your troops to the closest fan geyser (not including the two that stand in front of the enemy stage).

This will draw Ophelia and her main army away from her stage, which will allow you to stand in front of it and summon the Bleeding Death via guitar solo. When it arrives, the AI will then send back a decent amount of Grave Diggers to stop you, and summon more from the stage, which the Bleeding Death will dispatch with ease, thus earning you this achievement.

Is very easy, play in most gentle using tainted coil, i made it against drowning doom, upgrade ur stage to level 4 and dont let the AI upgrade, when level 4 u will get the option for call the unit Bleeding death is the last one and looks like an iron maiden, when the unit is ready u need to play the solo from the solo menu, u can see the same iron maiden thing, is that one, u need to stay close to the enemy units cause if u play the solo from a long distance from enemy it will do nothing , also wait for the enemy to have a lot of units, as u didnt allowed to upgrade it will deploy the weakest units and they come in groups of 6, just realese the bleeding death nearby and enjoy watching , hope u find this useful.