Dire (5e Template)
From D&D Wiki
Have you ever wanted to make a dire frog? Maybe a dire gerbil?
The creature you are modifying must be of the beast type.
AC. The natural armor is increased by one.
Size. The dire creature's size is increased by one category.
Speed. The beast's speed is increased by 10 feet.
Natural Attacks. The beast's attack die size is increased by one (d4 becomes d6, d6 becomes d8 and so on). If the damage die is a d12, add one die to the pool instead of increasing the die size.
There's a need for CR calculation for the increase in damage output, HP and AC.