Serious Sam 4

For this you need to complete all missions. This guide will mostly just be a guide for completing the final boss since I wrote guides for all other campaign mission achievements. So watch out for spoilers down below.

First, to make this easier make sure you have infinite ammo turned on and even tourism difficulty or play on co-op and set respawn timer to 0.
In the final mission you will need to get to the main battle arena, the main issue will be the final boss. Once you get to it you will get a grappling hook and parachute. You can use the grappling hook by pressing in the right thumbstick and the parachute works automatically as you fall. Use this grappling hook to launch yourself to what looks like purple tesla coils, don't even bother shooting the boss until all 9 of these are destroyed. You destroy them by launching and detonating c4 charges on these coils. 8 of these will be at identical locations on the bosses left and right side. 4 on left and 4 on the right. A few of these are on the legs, back of his hands, his lower back, and his arms. The final one will be found on the top of his head which is more easily accessible coming from the back of him and not his horns. Once all 9 are destroyed, parachute to the ground and get into the mech to finish him off and upon mission completion you will get this achievement.

Complete All These Missions on Any Difficulty

0.Man Vs Beast
1.Death from Above
2.Death from Below
3.Four Horsemen of the Apocalypse
4.Gates of Hell
5.The Die is Cast
6.Morituri Te Salutant
7.When in Rome
8.Machina Ex Deus
9.A Breakfast in France
10.One for the Road
11.Vive La Resistance
12.In Carcassonne
13.Anathema Unto God
14.The Package
15.From Earth With Love