It’s a bonus scaling modifier on top of a base 2% based on any damage done in the last twenty seconds, not just assist damage. It caps at 10% at 800 recent damage done. Melee weapons have a base of 15%, with bonus crit modifier capped at 45%.
That used to be an absurdly strong strategy in pubs, before the crit nerf 800 damage in 30 seconds got you up to the max of ~50% crit chance, 80% for melee.
So you'd just pop around a corner as demo and airburst stickies at the heavy until you got a crit, then go ham knowing half your shots were going to be crits and it'd be trivial to keep up 800 damage until the team was wiped.
It's been years since I've really played TF2 but I believe you can increase random critical hit chance by getting assist damage
It’s a bonus scaling modifier on top of a base 2% based on any damage done in the last twenty seconds, not just assist damage. It caps at 10% at 800 recent damage done. Melee weapons have a base of 15%, with bonus crit modifier capped at 45%.
That used to be an absurdly strong strategy in pubs, before the crit nerf 800 damage in 30 seconds got you up to the max of ~50% crit chance, 80% for melee.
So you'd just pop around a corner as demo and airburst stickies at the heavy until you got a crit, then go ham knowing half your shots were going to be crits and it'd be trivial to keep up 800 damage until the team was wiped.