Hello everyone, nice to welcome you on our site, this page even has Level 4 answers. I enjoy it =D
Level 4 - GUCNILR
The answer to this puzzle is:
Words: LURING, CLUING, CURING, RULING, RUNIC, LUNGI, RUING, UNRIG, CUING, CLUNG, RUNG, GIRN, CURN, URIC, LING, GNU, LIN, CIG, LUG, GIN, NIL
Bonus words:
LURING, CLUING, CURING, RULING, RUNIC, LUNGI, RUING, UNRIG, CUING, CLUNG, RUNG, GIRN, CURN, URIC, LING, GNU, LIN, CIG, LUG, GIN, NIL