I haven't really seen any threads explaining how this trinket works, so I browsed through a few logs. These are my findings so far, please correct if I'm wrong.
It's based on weapon damage (Felstorm is the damaging spell in logs). It can crit and multistrike. Looks like it's affected by player's Agi, Crit and MS buffs (starts to hit harder while player is under the effect of Draenic Agility Potion and starts to crit more when player has Detonating buff up). Looks like it's not affected by personal damage modifiers like Guile or FW (which makes sense, as it behaves like a pet and SR is not affected by those either).
Is there anything else that would be good to know about this trinket?
Here's Navv's post about SR mechanics for reference: click