The damage cap is a set value that represents the upper limitation of damage; that is, the damage cap cannot be exceeded in any stage of damage calculation. The damage cap value is 2,147,483,647, or (231-1). However, keep in mind that certain variable factors can lower a card’s realistic damage cap versus various spawns.
For example, if a card with three devil killer latents doles out one billion base damage versus a devil-type spawn, then the latent multiplier of 3.375 (1.53) would only boost base damage to the cap of 2,147,483,647.
Likewise, even if you blast an enemy for maximum damage (damage cap), an attribute disadvantage (i.e. Fire attacking Water) will cleave said max damage in half (to 1,073,741,824). Since attribute disadvantage, defense, and damage reduction shields (in that order) are factored in at the end of damage calculation, realistic damage caps can be much lower than the actual value. Do note that cards can still reach the numerical damage cap even if hampered by an anti-burst effect, as long as other multipliers are high enough to indirectly counter it.