Trying to make DIO mod

I’m making mod, that adding DIO (from JJBA) profession, his Vampirism and his Stand… But problem is I’m poor mod maker, so I can’t realise everything I want and now it’s even crashing without error, so I’m asking for help.

What has already been implemented:
Vampirism Mutation,
DIO profession,
Stand (as ally monster)
Spell of Summoning and Recalling Stand (Basically, just dealing allies 1000 dmg, which is kinda bad I guess).

What needs to be done:

Make Stand follow PC,
Change how recalling works,
Make cooldown to Summon spell (so you can’t spam summoning),
Increase the chance of spells to trigger to 100%,
Todo: Time-stop ablitiy

Crashing:

Currently, when I try to select “Summon Stand” spell, game crashes. Dunno, if it’s mine problem or it’s will be same to you, but it’s need to be fixed.

I would be grateful for any help!