PS4 Resident Evil 5 Mercenaries United Solo Ancient Ruins Wesker Midnight 150 kills

well, again. took me 2 weeks to get this 150 kills in ancient ruins after spending 2 weeks to get it in the village. still don't know why i struggle since wesker is the most powerful character? may be i should post the videos of the ones i failed, then you people can tell me what i did wrong?