Dual Initiative, Average Damage, and Calculating CR. Do you count both turns, or only one?

[Reksew_Trebla]

Just as the title says. I’m trying to calculate the CR of creatures who have dual initiative, using the Monster Creation rules, but I’m not sure if I should count both turns or only one turn for average damage.

[Claxon]

Mythic Rules (like Dual Init) are real hard to determine what the CR is. Do you really need to know for XP or are you just trying to make sure the enemy is the appropriate difficulty?

Because the second one is more important in my opinion, and but doesn't really care about rules.

If you're using it as an encounter on it's own I would say it's just kind of a baseline need against an mythic PC party.

Hell based on what I've seen of Mythic the PCs will either kill it on round 1 or be killed by it on it's first turn.

[SheepishEidolon]

You could argue either way. A possible comparison would be two creatures instead of one: Twice the damage potential, double HP, less vulnerable to single-target effects but more to AoEs, for +2 CR. Another one would be the agile template, granting dual initiative and a few more buffs, for a measly +1 CR.

I'd use the creature's first round for buffs and getting into position. Killing PCs with sudden bursts of damage helps to challenge the group as a whole, but it also drives players deeper into "we must kill it before it kills us" territory.

[Reksew_Trebla]

Claxon wrote:

Mythic Rules (like Dual Init) are real hard to determine what the CR is. Do you really need to know for XP or are you just trying to make sure the enemy is the appropriate difficulty?

I was going to advance a Mythic Hydra, which has Dual Initiative, but I noticed that the developers decided it was too powerful for a CR 8 (Hydra CR 4, plus Hydra Advancement of 2 more HD, as called out in their bestiary entry, which increases to CR 6, then MR 3 is the same as +1.5 CR, which for the Mythic Creatures, I’ve noticed they seem to always round up in CR increases, so that results in CR 8), so they brought it up to CR of 9.

If I increase its HD as called out in the Hydra entry, where every extra HD gives it an extra starting head, an additional +1 to nat armor, and +1 to CR, I’m afraid that with Mythic Hydras having Dual Initiative, it would end up not balanced for its new CR. It would either end up too weak or too strong knowing my luck in trying to decide which way I should swing for average damage.