Hints Path of Valor is just the first "Path" in a routine

[zephyr1]

@Dragonst666

Or is each tier going to count for event completion?

Yes:

@zephyr1

Complete a Challenge Event

NOTE: Each tier (Rare/Epic/Legendary) of a Challenge Event counts as completion, so long as you complete all 15 Stages in that tier.

Both Knights of Avalon and Pirates of Corellia will be during this Path of Valor, so there will be up to 6 Challenge Event “completions” available.