Styx: Master of Shadows
33 Achievements
25-30h
Indigestion
Kill an enemy by poisoning the food
21.7%
How to unlock the Indigestion achievement in Styx: Master of Shadows - Definitive Guide
Now just wait for the first and then second guard to die.
EDIT: You don't need your clone, you can puke in the fruit bowl, too.
Bloop - 15GS!
This can be earned any time you see a fruit bowl on a table or a food bag hanging up.
Mission 1: Akenash's Atrium has a lot of these and is early in the game.
Run up to one when no one is watching and press to spit in it. Then hide somewhere nearby and wait for a patrolling guard to eat from it. The poison takes about 10 seconds to kill them and then your trophy unlocks.
Note: Choose a target that guards frequent, not one in an area where you've killed everyone.
Here's a video example:
There are a handful of places where Styx can poison food or water, but the first time the story-line mentions it is easiest place to "not miss it". In the mission Akenash's Atrium (Mission 1) you will eventually get to Zone 2, which is named Embassy.
Shortly after entering Zone 2 you will eventually be required to go through a door that has 2 guards close to your position, they are facing each other and will be standing next to a desk with fruit on it. You'll know you are in the right place as the game story will encourage you at this point to poison the fruit; Styx will even make a verbal comment about it. You do have to be swift or you will probably be detected but you can always reload a save if that happens. Obviously they won't eat the food if they are in red alert status against you.
Move immediately to the fruit, press to poison the food, then press to crouch to the right around the edge of the desk. Press again at the desk corner to move around it, and then yet one more time to successfully move underneath the desk (where you cannot be seen).
The first guard will eat the fruit then walk right in front of you position (but if you are under the desk he will not see you). Immediately after the second guard eats the fruit, the first guard will croak. The second guard will go into an orange detection status but will soon croak after that as well. The trophy will pop as soon as the first guard dies.
Video guide by rus199410 in a different location:
By poisoning a fruit basket or poisoning drinking water.
Here are my videos with both methods.
1) Poison using a fruit basket
2) Poison using drinking water