Exploring an area in stealth while having Interloper, you are free to initiate combat with Snipe for example. If you hit ENTER first, so switch to combat mode in advance before doing any attack, you get your 15 MP no problem.
But if you just hit Snipe without stopping time, the game of course only switches to combat mode as soon as you perform the shot. But this way you won't give you your 15 MP regardless if you're having Interloper or not.
