So me, my sister, and some of her friends were playing D&D last night. We got into a mini boss fight, and I rolled to go third in initiative. Ash, a Tabaxi Artificer, rolled ten in damage on her metal bird. The mini boss attacked her back, leaving me next. I rolled a NAT 20, WHICH IS A CRITICAL HIT IN THE CRIT RULES MY SISTER HAD SET UP. I rolled a 16 in normal damage, and due to some complicated math I didn't bother listening to, my Witch Bolt did 40 damage over 16.
The mini boss was at 61 HP.
I dealt 40 damage.
LEAVING IT AT 21 HP.