A discussion about anti-heal for ADCs:

Uh, Freya you can definitely go Obs Shard if you're ADC and need to shred the frontline, but you also consider Magus again since they made her 1 spread into 5 instances of damage. In regards to the low squishy pen, Freya already will have over enough dps to squishies with the rest of the items she will build.

As for Chronos/Sol, Obs Shard is absolutely functional due to their ability poke, as well as the fact that demonic needs to be stacked to be effective while in lategame teamfights you're going to need that % pen quickly to shred the front line as fast as possible.