Contagion is a necromancy spell that requires an attack roll and a "best of 5" save mechanic to inflict a disease. Is this a good spell? Check your odds against the whole gamut of monsters.
Flanking is an optional rule in the D&D Dungeon Master's Guide that grants players advantage when their characters attack opposite sides of an enemy. This optional rule can enhance tactical aspects of your game. Understanding more about how this affects different characters can help you decide when to use flanking in your campaign. If you're a player who knows your DM employs the flanking rule, this may help you avoid some pitfalls.