# How are summons' HP determined?

I'm new to summoning. When you summon a creature using any of the spells, how do you decide what the HP should be?

Take for instance the medium gravity elemental who has 4d10 +12 but is given 24HP. So while it IS possible for 4d10 to total 12, its less likely as the average of 4d10 should be around 22 (as 2d10 should average around 11), which is still a far cry from the highest of 40. So is this a case of taking an average or can we decide to roll?

• It seems this average is completely off - the average of 4d10 is 22, so this thing should have 34 hp average. – Erik Sep 13 '16 at 7:05
• opps, the thing I looked at for the average number was a drop the lowest thing – Fering Sep 13 '16 at 7:14

I'd like to refer you to this question and answer: Is the hit die supposed to be rolled.

## Monsters can sometimes use shortcuts.

Often, it is impractical to roll the HP for every individual monster. While they technically use the same rules [as player characters], it is also acceptable to use an average amount of HP for them without rolling. The Monster Manuals automatically give you what this amount would be in parentheses for your convenience. If you don't feel like rolling, simply use these amounts for all monsters.

And also this question and answer: Why is a dice roll required when doing a creature HP check?

The dice roll is to determine how many HP a particular creature has, since it makes sense that they're not all identical. However, when it appears after a number of HP that means it has already been rolled for you, and the roll is just there for informational value.

Whilst unfortunately I have no proof, I do agree with Erik that it looks like it ought to have a 34HP average, rather than 24HP and this is just a typo. This would make it consistent with the Small and Large elementals.

I would recommend discussing this with your GM and hopefully agreeing on 34HP as being the correct value.

• Indeed it looks like a copypaste typo. Considering the origin (tome of horrors), thats not surprising. – ShadowKras Sep 13 '16 at 11:52
• I was picking a random elemental and that was sounded cool, so just my luck to end up with an incorrect entry, lol – Fering Sep 13 '16 at 16:16