The summoner in our party has an eidolon with a 1d6 (fatal d10) primary attack.

Primary Attack: Choose from the following statistics for the more flexible primary attack.

  • 1d8 damage (disarm, nonlethal, shove, or trip)
  • 1d6 damage (fatal d10)
  • 1d6 damage (forceful and sweep)
  • 1d6 damage (deadly d8 and finesse)


The fatal trait includes a die size. On a critical hit, the weapon’s damage die increases to that die size instead of the normal die size, and the weapon adds one additional damage die of the listed size.

The summoner casts runic body (aka magic fang) on the eidolon

Glowing runes appear on the target’s body. All its unarmed attacks become +1 striking unarmed attacks, gaining a +1 item bonus to attack rolls and increasing the number of damage dice to two.


A striking rune stores destructive magic in the weapon, increasing the weapon damage dice it deals to two instead of one. For instance, a +1 striking dagger would deal 2d4 damage instead of 1d4 damage.

This makes the eidolon's unarmed attack deal 2d6+4 damage.

On a critical hit, the fatal trait makes those dice d10 and doubled the total (before an additional d10 is added from fatal), so ((2d10+4)*2)+1d10.

In our very first session the eidolon crit on a golbin and dealt 42 damage. The average of the roll above is 35.

Just checking to see if we are doing everything correct here? That seems insane for level 1.


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    \$\begingroup\$ I went ahead and added relevant links to Archives of Nethys. One thing I couldn't find is what I think is the crux of your question: Runic Body. Can you provide a link indicating where that comes from? I could not locate it as a 1st level spell from any tradition, nor could I find a summoner focus spell that seemed to match it. \$\endgroup\$ Commented Jan 16 at 20:33
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    \$\begingroup\$ @Pyrotechnical Runic Body is the Remastered name for Magic Fang: 2e.aonprd.com/Spells.aspx?ID=179. I think at first level/rank they have the same effect, but Runic Body has heightening. \$\endgroup\$
    – ESCE
    Commented Jan 16 at 20:39
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    \$\begingroup\$ What are the +3 and +1 on the damage? \$\endgroup\$ Commented Jan 16 at 20:40
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    \$\begingroup\$ @KiernanNicholls does this answer your question (or help)? rpg.stackexchange.com/a/159258/64464 \$\endgroup\$
    – ESCE
    Commented Jan 16 at 20:43
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    \$\begingroup\$ @ESCE Yes it does! The eidolon's unarmed attacks are essentially a pick with striking and the math they list there is similar to what we came up with (minus the specialization damage). \$\endgroup\$ Commented Jan 16 at 21:52

1 Answer 1


The damage is correct (if your modifiers are)

Pathfinder 2e uses simple doubling rules for critical damage, only slightly complicated by the Deadly and Fatal traits (and similar effects). For 1d6 damage on a crit, you roll 1d6 and double the number. For 1d6+1, you roll 1d6, add one, then double the total.

You used Fatal correctly. A Fatal d10 weapon deals [(1d10+modifiers)*2 + 1d10] on a crit.

To address your reason for questioning this, it's simple. Runic Body and Runic Weapon are extremely potent at first level. They're giving you a level 4 item. On a d10 weapon, this increases the average damage of a hit by 5.5 and crit by 11 damage. Critting for 24 (11 less than the average you calculated) is not unusual at level 1. Rogues, Barbarians, and Gunslingers all easily reach the mid 20's when they crit.

You might have the modifiers wrong. I would guess the +3 is from Strength, but I'm not sure where the +1 damage comes from and a +1 weapon/attack does not get +1 damage. Striking is the only increase to the base damage of a weapon. I know that doesn't suddenly make the damage total reasonable, but it's worth correcting if I intuited correctly.

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    \$\begingroup\$ Yes, I wrongly assumed that the "+1 striking weapon" from runic body added +1 to damage like in D&D 5e! Good to know, thanks. Sounds like the bulk of the damage from the extra dice and all the doubling is right though. \$\endgroup\$ Commented Jan 16 at 21:37
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    \$\begingroup\$ @KiernanNicholls glad my intuition served me well. I hope you like the system more than 5e when you get used to it, I know I do. I will also note that I wouldn't be overly worried about the Eidolon's Fatal damage with Runic Body up. Runic Weapon could be cast on a Fighter with a Greatpick and have them dealing that kind of damage more often. After a couple levels, the system gets its feet under it (levels 1-3 have historically been very difficult to balance) and accounts for similar combos. \$\endgroup\$ Commented Jan 16 at 22:34

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