Hello everyone, nice to welcome you on our site, this page even has Level 4 answers. I enjoy it =D
Level 4 - YCLLBIPU
The answer to this puzzle is:
Words: PICUL, CULLY, PUBIC, ILLY, CULL, YILL, BULL, BLIP, CLIP, BILL, YIP, PIU, LIB, ILL, PIC, BUY, LIP, YUP, CUP, CUB, PLY
Bonus words:
PICUL, CULLY, PUBIC, ILLY, CULL, YILL, BULL, BLIP, CLIP, BILL, YIP, PIU, LIB, ILL, PIC, BUY, LIP, YUP, CUP, CUB, PLY