When I DMed, I'd put every monster the PCs fought on an index card.
Now I had a thought.
4e monsters all have roles. Each role has different HP/Damage bonuses/etc. With the New Math, their stats don't matter so it's all based on level and role.
So instead, just make a card for each role that has that role's HP/Defenses/standard +damage. Keep these cards pinned to your DM screen/in your folder. Each time your PCs level up, level up the monster cards.
Then, you only need to just write down specific power expressions.
This way if you ever have to do an encounter on the fly, you have all the HP/Defenses right there.
Now I had a thought.
4e monsters all have roles. Each role has different HP/Damage bonuses/etc. With the New Math, their stats don't matter so it's all based on level and role.
So instead, just make a card for each role that has that role's HP/Defenses/standard +damage. Keep these cards pinned to your DM screen/in your folder. Each time your PCs level up, level up the monster cards.
Then, you only need to just write down specific power expressions.
This way if you ever have to do an encounter on the fly, you have all the HP/Defenses right there.