[Arknights] Obsidian Festival Low Level Strategy
This video covers only OF5 to OF8, and OF-F2/3. Other stages has a recommended level of below Elite 1.
Read pinned comments for stage specific tips.
The stages are filled with high magic res and low armor targets. Even the big axe dude has only D defense despite their high armor appearance. This means that without appropriate magic supports (Eyjafjaara, Ifrit, Saria), your magic units likely won't do anything.
I used no 5* operators (other than a lv30 Ceylon, which you will get from clearing OF4), but most of the 5/6* operators of the same class will be superior, and allow for alternate strategies.