When affected you take increased damage, certain items grant this effect on certain conditions, usually if the item is really useful or really powerful it will have marked for death for game balancing.. Marked for death makes all incoming damage minicrit unless otherwise specified. It also lingers for a bit (usually 1-2 seconds) after the item is stowed so you can't turn off the downside immediately.
Marked for Death is a Eternity Mode exclusive debuff inflicted by certain enemies. It multiplies all base damage received by 1.5 and displays a harmless spinning skull above the player. Dying while affected by Marked for Death causes the death reason to always display as " (Player name) was reaped by the cold hand of death," no matter how the player actually died. The player can become immune.. After death, the player is placed in the respawn cycle and must wait a certain length of time before rejoining the game. During this time, the player will temporarily enter spectate mode, unless instant respawn is enabled on the server. In Mann vs. Machine mode, a player's death is broadcast to all teammates via a sound cue.