Massive Creature Traits
Creatures of huge size or greater are truly imposing foes, possessing colossal strength and weight. Unfortunately, the statbocks in the monster manual rarely give justice to these traits.
Consider adding any or all of the following features to creatures with a significant size advantage over their foes.
Immovable. This creature cannot be moved or knocked prone against its will by objects and creatures two or more sizes smaller than it, except by magic.
Vast Reach. (+1 CR) When this creature makes a melee attack, apply the attack to each creature within an area. Depending on how the attack is described, make the area either a flat 5ft thick cone (representing a swipe or slash), a 5ft wide line (representing a thrust), or a cube centered on a point within the attack range (representing a stomp or smash). The length of each area is equal to the attack's reach. Roll the attack once and apply it to each target.
For example, an Adult Red Dragon might have a tail attack as a flat 15ft cone, and a bite attack as a 10ft cube.
Colossal Might. When this creature hits a target two or more sizes smaller than it with an attack, you may have the target make a strength saving throw against a DC equal to 10 + this creature's Strength Modifier. If it fails, you may knock the target prone and may push it 10 feet in a direction of your choice.
Trample (+1 CR) This creature can share its space with creatures two or more sizes smaller than it, and neither provoke opportunity attacks from the other.
When this creature moves during its turn, each creature whose space it passes through must make a dexterity saving throw with a DC equal to 10 + this creature's Strength Modifier. If it fails, it falls prone and takes bludgeoning damage equal to 1d10 + this creatures Strength modifier. A creature can be subject to Trample only once per turn.
Artist: Ignacio Bazan Lazcano
Colossal Size
The largest official creature size is Gargantuan, at 20 by 20 ft. If you create a new creature of greater size, or believe that the stats of an existing creature falls short, consider granting it the Colossal size.
Colossal size starts at 25 by 25ft and increases from there. Each creature of Colossal size has its precise size listed. For example, following cannonical proportions, the tarrasque should have the following classification at minimum:
Colossal (50 by 50 ft) monstrosity (titan), unaligned.
For effects that scale with a creature's size, consider a Colossal creature to be 1 size larger than Gargantuan for each 20ft in its dimensions above 20ft, rounded down. A 25 by 25ft creature is one size larger than Gargantuan, a 45 by 45ft creature is 2 sizes larger than Gargantuan, and so on.
