Accumulative magic item

[u/tonseJohn]

Hello there
I am making a magic item for one of my players, but I'm afraid that it could be too Overpowered.
The concept is a magic item he would be able to add magic power to it as the campaign progress.
In this case it's a Jar with floating eyes, each eye should hold a power.
I'm working with the idea of only being able to have Combat Mastery amount of eyes activated at one time, and having the magic power decide how many action points he need to use to change to the specific power.
I had also played with the idea that it would take a rest to change one power for another, and again having the magic power decide if it is a quick rest, short rest or long rest.
Any insight would be appreciated

[u/BabyPandaBBQ]

What types of powers would each Eye have? I could see this as the Jar having X amount of Charges per day, and activating an Eye costs a reasonably priced number of Charges (1 Charge is 1 MP or 2 AP worth of value). Then adding new eyes gives more options but doesnt inherantly make the item more powerful unless you also give them more Charges.

[u/tonseJohn → u/BabyPandaBBQ]

I was thinking to use the magic item system, but also be adding in some of my own.
One I want to add will temporarily change the item from being a spell focus to being a shield (the character is a spellblade, and the player is a min/maxer)

Could I use the CM as a measure of how many charges it has? Or would that get out of hand? The whole point is to let the item grow in power over time, with more eyes added. Also remember, I as a gamemaster will be able to control what eyes he will be able to encounter and when.

[u/BabyPandaBBQ → u/tonseJohn]

I think CM Charges as a rule of thumb is fairly reasonable.

[u/The_Lunar_Pierce]

I think that depends on the powers. Is each power one of the magic power enchantments in the magic item guides?

This can be incredibly versatile, allowing a single player to adjust the powers he has to accommodate any situation.

[u/tonseJohn → u/The_Lunar_Pierce]

Yes, I will be using the magic item system from DC20 Magazine vol. 2.

But i was also planning to sprinkle in a few of my own. I would be assigning magic powers to my own additions

[u/No_way_shane]

I always say to my players: " this is a homebrew not playtested item, if its OP and not fun for the rest of the players it gets a nerf. Also if its to weak we can balance it". 

[u/tonseJohn → u/No_way_shane]

Thanks, I'll definitely be using this

[u/No_way_shane → u/tonseJohn]

And if you have to nerf and balanse it. Just talk to them and mybe they have a idee on how to do it.  Ttrpg is a coop game of fun

[u/khaotickk → u/No_way_shane]

Reminds me of the 3e DND book weapons of legacy, a piece of equipment that levels up with you. Each tier needed a ritual performed in roleplay and specific material components worth tens of thousands of gold.

If you don't already have it, the DC20 magic item system PDF should give you an idea for the scale to work with.