So did he forgot about the Golgari Warrior that went through his physical defenses like a hot knife through butter. Normal golgari should not matter to Anthony because Anthony's sisters will be more than enough to deal with them.
What should be his main focus is guys like that warrior who make his current physical defensive setup useless and I am going to assume there exist mages who can do similar things to Anthony. His main focus should be mutating himself to deal with powerful opponents one on one, since his magic gives him more than enough power to mow down hordes of weaker enemies.
Thus far he has done a great job at slowly inching towards that goal but he for someone reason forgot about his latest challenge, whoever that Golgari warrior is. Finding more physical defense mutations to add on to his current catalogue should be priority #1.
By not specializing Anthony leaves himself little major weaknesses for people who do specialize in certain field to exploit. This style of build has worked, up until a Golgari warrior who obviously specializes in physical offense made Anthony's physical defense meaningless. Hence he needs to do something about that ASAP, either through mutation or through equipment.
Also Anthony does have the chance to alter his mutation build slightly to beat that guy which is something that guy should not be capable of doing for himself. Meaning, he cant adapt as quickly as Anthony can, probably, and judging by his arrogant behavior, I dont think he would even if he could.
In fact, maybe Anthony can use Mind magic and psychological warfare to take advantage of that arrogance to do something to that warrior. Similar to how he beat Garralosh when she was ,and still probably is, significantly stronger than he is. However, I do not think such an obvious psychological weakness would not be thought of by the Golgari and their mages especially after fighting Anthony.
Of course, the Golgari might be able to make equipment for that warrior or somebody else, to specifically deal with Anthony and that is the only way they can adapt almost as quickly as Anthony can with mutations(or at least the only way I can think of). Hopefully the ants crafters start to catch up and allow Anthony to have the same advantage.
The only caveat being, if the Golgari are a monster species and have access to mutations, Anthony might be in very big trouble. Anthony might not be willing to mooch off of his siblings Biomass but I dont think that Warrior will have the same amount of integrity. He might even be more inclined to do so because he could not kill an ant and I highly doubt his fellow Golgari will be understanding of his failure.
The sticky mana eating acid that grows was actually my thoughts for next acid upgrade. It synergizes well. Then after tier 6 pump up the mana eating capabilities.... or a mana destabilizing property to make it harder for the poor sap covered in it to even use spells to get rid of it. Maybe a baseline intelligence that turns it into a semisentient goop that follows your orders?
Some ideas for Crinis:
1: Warrior like skills. Apply sword beam attacks to her tentacles.
2: Defensive measures. Partly out of a desire to be better armor for Anthony, she can learn to project a barrier around her shadow flesh. This could let her disperse attacks on Anthony's carapace. She could also use this to grip bladed weapons with her tentacles and resist being cut. When Anthony gets his armor, Crinis can act as a liquid layer to help distribute the force of blows.
Offensive magic: Beams fired from both the ends of her tentacles as well as mana infused barbs to let Crinis use a mind bending number of off angle ranged attacks.