|2 people marked this as a favorite.
There are guidelines in the Building Creatures rules regarding Active Abilities that give very good guidance.
Consider how you want your creature to spend its turns. Two-action activities pretty much define the creature’s turn, and single actions work best for supplemental benefits or normal Strikes.
Use 3-action abilities sparingly, as a creature can’t use them if it is slowed or stunned—making a creature’s coolest or most defining ability use up 3 actions might mean the creature never gets to use it. These activities should be reserved for abilities that include some movement (like Trample) or that the creature is likely to use before engaging in combat. Don’t make an ability use 3 actions as a way to balance it—saying “This can be more powerful than other abilities because it is less likely to work,”