Start with roles, not a tier list
A formation is more useful when you understand what each hero is doing. Tanks absorb pressure, carries provide damage and supports contribute utility. The current Haven roster records those source-described roles, which is a safer starting point than pretending one lineup is universally best.
Compare formations in context
When you test a lineup, record where you used it: PvE, PvP, an event or another specific encounter. A formation that looks strong in one situation may not tell you much about another.
What to record
Note the three hero slots you actually used, your troop mix if known, the battle or event context and the result. If you have a screenshot or date, keep that too so you can compare changes later.