Earlier this week, I took a look at Bloodied and Bruised from the DMs guild, which is a 5e DMs Guild product that introduces new effects for D&D monsters that trigger when monster drop below 50%, given them new reactions, and in some cases, adds in death throes.
I really like the idea of monsters that change tactics as the fight evolves, so I wanted to give this product a closer look. Swing by if this sounds interesting.