| Shinimas |
I've playtested the Magus a little bit. I think it's somewhat weak, but I'll start with the things I like.
The limited spell slots and slot progression. This is fine, it frees up design space. It allows to give Magus better martial capabilities, forces the player to pick fitting spells, which emphasizes the Magus as a warrior, not a universalist that relies on magic to deal with all his problems.
Armor and weapon progression. Proper martial level and should stay like that.
Arcane only. Again, I like it. No need to make every caster capable of every spell. Specialization is good.
Now, the bad stuff.
Squishiness. D8 hit die is not a lot of HP. D8 combined with 12 CON (14 if you're going for Heavy Armor) is just not enough for a class that's forced to stay put in melee. Plus your supposedly martial spells trigger AoOs.
All or nothing. So much preparation, so many abilities used, resources spent... and then you miss. This leads to a very disappointing feeling. You miss, your turn ends, nothing's done.
Tactical limitation. Your optimal turn takes all 3 actions. There are cool feats like Spell Parry, but why would you use it? +1 to AC and Saves and now you're a Rogue without Sneak Attack and even worse defenses. I don't think using your class feats should lock you out of your main class ability. Demoralizing, Grappling, casting Shield etc.? Do any of that and your combat effectiveness plummets. Other classes are encourages to try something else either than striking thrice. Magus is backwards in this regard.
What can be done?
Striking Spell should be buffed. Free Action to prepare a single target spell, then you cast it and make the Strike as a part of the cast, replacing the Somatic component with the swing. The spell loses the Manipulate trait. MAP only increases after both Strikes are made. If your off-hand isn't free you take a -1 penalty to the spell attack roll. Now it's like Double Slice, but with a spell. Weaker than Double Slice if you're using a Cantrip, stronger if you're using a slotted spell.
Slide Casting should be made a high level class feat. Sustaining Steel should work with all melee weapons.
Now you're free to take Sustaining Steel and become just a little bit tougher, which is needed to survive in melee.