The Hand of Merlin
54 Achievements
GOG
Exertion
Use 4 action points with a single character in one turn.
12.8%
How to unlock the Exertion achievement in The Hand of Merlin - Definitive Guide
SlayerNZ
There's a few relics and bonus encounter rewards that give extra AP. The easiest ways I found was to use Merewen the Ranger, and get the Archer skill, Hunter's Spree, which if your shot is fatal you regain 1 AP. Have 2 enemies in shooting distance with low HP, shoot them both and kill them and then use the 2 remaining points to shoot something else or move. Just make sure it's not the last two enemies left as the fight will end!
Or if you get the haste skill, one of the final upgrades for it is 2AP - use this (you will need another skill will 0 cooldown) and the trophy will pop.
Or if you get the haste skill, one of the final upgrades for it is 2AP - use this (you will need another skill will 0 cooldown) and the trophy will pop.