From Brotato Wiki
Rip and Tear cannot crit, and it does not trigger life steal. Enemies killed by Rip and Tear can also cause Rip and Tear to trigger on their deaths. Be mindful that picking up Rip and Tear can severely reduce the amount of healing you get from life steal in general, if the explosions are killing enemies that would otherwise have been hit by your weapons.
Both the damage and the chance to cause an explosion increases when you gain additional Rip and Tear items. So the chance for an explosion is 20%/40%/60%/80%/100% as you get up to 5 of the item. And the damage also scales up to 50 + 250% of your Melee damage when you have 5 Rip and Tear items.