Have your XCOM Squad go from 100 health to 0 in a single AI turn.
Requirements[]
Brave New World
Strategy[]
You need to allow your XCOM Squad to be killed in a single AI turn. There's a cheap strategy, though it may be a bug in the achievement. It seems the game doesn't really check if damage occurred on the AI or your turn, so to get this achievement you may simply start a game in atomic/information era, move an XCOM squad away from your cities and drop two nukes next to it. This should be enough to kill it, at least that's how I got this achievement. If you nuke the tile your unit is on, you will not trigger the achievement, it must die from splash damage.
Trivia[]
This is Xcom baby is a reference by fans of the unfair nature of Xcom as players can lose members in a single turn thanks to RNGesus getting them killed