Hello everyone, nice to welcome you on our site, this page even has Level 4 answers. I enjoy it =D
Level 4 - IGVIDRN
The answer to this puzzle is:
Words: RIVING, INDRI, IRING, VIRID, DING, RIND, GIRD, GIRN, GIN, DIN, VID, RID
Bonus words:
RIVING, INDRI, IRING, VIRID, DING, RIND, GIRD, GIRN, GIN, DIN, VID, RID