bone offering tooltip improvement and damage scaling

Some more skills and interactions that would benefit from more/clearer information:

Bone offering's explosion does not show its damage in the skill panel.
Does it scale with minion or player damage (or at all)?
can it crit, etc.?

On a related note:
necromantic talisman + fireflower + infernal legion lets minions ignite, which deals damage to them, is this damage a hit that should trigger bone offering?

It feels like explosions happen more frequent in this arrangement, but not as much and as reliable as i think it should. Is there a hidden cooldown?

thanks and kind regards