Ki spell and saves

Hello, for example, medusa's wrath is a ki spell ?

Which save must an opponent take against the DC ? Fortitude ? Will ? Or Reflexe ?

The spell asks for a Fortitude save. When calculating a Monk's spell DC, your key spellcasting ability is Wisdom.

Medusa's Wrath is a ki spell but the initial effect is not tied to saving throw but a Strike. After the strike hits they make a fortitude saving throw at the end of their turns against your spell DC.

With brawling focus, if the strike is a critical, does the - 4 penalty to saves apply on the fortitude save for medusa's wrath ki spell ?

I don't see anything in Brawling Focus about a –4 penalty to saves.

(I don't know what other feat you meant; Monks aren't my forte)

But the effects of Medusa's Wrath are described as "additional" to those of your Strike.

The DCs would be different, though. Critical Specialization for Fist uses your Class DC.

If you're talking about the grievous rune it is only referring to the save done with the brawling critical specialization effect.

Is it possible to use medusa's wrath with wild wind initiate ?

Does Medusa's wrath apply on several attacks on the same turn ?

Is it possible to use medusa's wrath with wild wind initiate ?

No, Wind Crash and Medusa's Wrath are two different types of attacks. Same as carrying around two different weapons or having two different unarmed strike options.

Does Medusa's wrath apply on several attacks on the same turn ?

It is one attack. It doesn't modify other Strikes, it tells you to make a Strike as a subordinate action and modifies the results of that Strike specifically.

Medusa's Wrath is an Activity that involves making an unarmed Strike. It doesn't matter which unarmed Strike. A Wind Crash Strike is as valid as a Fist, Claw, Bite, Falling Stone Strike, Seed Pod, etc.

Medusa's Wrath is an Activity that involves making an unarmed Strike. It doesn't matter which unarmed Strike. A Wind Crash Strike is as valid as a Fist, Claw, Bite, Falling Stone Strike, Seed Pod, etc.

Hmm... That is interesting.

Subordinate Actions. Medusa's Wrath says to make an unarmed Strike. You can't replace a basic Strike action with Flurry of Blows, Ki Strike, Flying Kick, Ki Blast... So it seems really unintuitive that you could use Wind Crash, Falling Stone, Seed Pod, or Foxfire with it - but I think you are right that those do work.

Wind Crash, Falling Stone, Seed Pod, or Foxfire are all basic Strikes, so I don't see where it would be ambiguous. The only part that seems unintuitive is if you assume (as many people naturally do) that there would be a requirement of being unarmed melee Strikes.

I don't think it is ambiguous. I think you are right.

What I find unintuitive and unexpected is that the focus spell for Wild Winds works with Medusa's Wrath, but Ki Blast doesn't. It just creates a bit of a gotcha that non-rules-lawyer players may not notice. I didn't notice the difference initially until you pointed it out.

I think I was looking at it from the perspective of "That's a level 16 feat, and monk players have been dealing with the distinction between specific Strikes and abilities that make Strikes as subordinate actions since level 1"

I mean, Ki Blast is an activity and Wild Winds/Falling Stone/etc. are essentially weapons. They aren't really equivalent.