What is the point of Bestial Mutagen?

The Bestial Mutagen gives you a penalty to AC and Ref, but also unarmed attacks, and an item bonus to these. The bonus to attack is 1 higher than what you could get on a level-apropirate weapon, which is nice, but the damage is really lacking after about level 4, more than offsetting the attack advantage:

  • level 4 (4.5 vs 7 damage)
    • Bestial Mutagen: 1d8, or 1d6 agile
    • Weapon with Striking rune: 2d6 or 2d4 agile
  • level 12 (5.5 vs 10.5 damage)
    • Bestial Mutagen: 1d10, or 1d8 agile
    • Weapon with Striking rune: 3d6 or 3d4 agile

Based on this Mutagenists are better off just using weapons, but Bestial Mutagen is supposed to be their signature ability. As Pathfinder 2 is one of the best balanced games I have ever seen, I am pretty sure I am missing something, but what?

How does a Circle of the Shepherd’s Mighty Summoner feature interact with the UA spell Summon Bestial Spirit?

Our DM has allowed us to play-test the summoning spells which appear in Unearthed Arcana 2020: Spells and Magic Tattoos and I have added the 2nd-level Druid spell Summon Bestial Spirit (pp. 3-4) to my spell list.

I chose the Circle of the Shepherd which has a feature at L6 called Mighty Summoner, which is meant to enhance a druid’s summoning/conjuring spells by adding +2 HPs per Hit Die and causing the damage to be classed as magical (XGE, p.240).

For example, with the 3rd-level spell Conjure Animals (PHB, p.225), if I conjured a Giant Boar (MM, p.323), it would have an additional +10 HPs because it has 5 Hit Dice (5d10 + 15). So the conjured/summoned creature would have 5d10 + 15 +10 HPs in total.

Here are the relevant parts from the UA spell:

Summon Bestial Spirit

You call forth the spirit of a beast. […]

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, the creature assumes the higher level for that casting wherever it uses the spell’s level in its stat block. […]

Hit Points equal the beast’s Constitution modifier + your spellcasting ability modifier + ten times the spell’s level

In the case of the Summon Bestial Spirit the creature’s HPs are linked to the spell level, so how does it interact with druid’s Mighty Summoner feature? Does the spell level determine the Hit Dice?

I would appreciate an answer with an example and/or experience of having play-tested this spell.

Does the attack from a Mystic’s Bestial Claws take an action?

This question is about the UA Mystic (v3).

The Bestial Form Immortal Discipline has this possible effect:

Bestial Claws (1-7 psi). You manifest long claws for an instant and make a melee weapon attack against one creature within 5 feet of you. On a hit, this attack deals 1d10 slashing damage per psi point spent.”

The vast majority of Mystic effects specify that they take an action, a reaction, a bonus action or a given number of minutes, but this one doesn’t specify anything in that regard. Does it mean that “Bestial Claws” doesn’t use up an action ?

If so, this would mean that you may take the Attack action, and then do an additional attack with this effect. Furthermore, I didn’t see anything that prevents a Mystic from using several effects on the same turn, so would that mean that he can make as many “Bestial Claws” attacks as he wants (provided he has the psi points) in one turn ?