When you swing a longsword, roll a d20 and add your Strength. If the total meets the target’s Armour Class, the blow lands for 1d8 slashing.
A creature knocked down is prone: attacks against it roll twice and keep the higher until it spends half its movement to stand.
When the fireball blooms, every creature inside makes a Dexterity save against 15, taking half on a success.