I have two main reasons why 40 geodes for this upgrade annoy me.

First off, a lot of the upgrades are not worth 40 geodes. The perpetuation staves come screaming to mind. You trade in 40 geodes to get -2 Blood Pact ability delay. No extra perp, no special effects for the pet. Just -2 Blood Pact ability delay which you are already capped on. It would be different if this was a special BP delay that went beyond the -15 cap, but it does not. And the funny thing is that perp cost went up by one between level 90 and 95, so even upgrading won't break even with the current perp costs.

Secondly, how much is the next upgrade going to cost? Going from 15 to 40 is a 266% increase. If they did a similar increase for level 99, it would cost 107 geodes. Hopefully it won't be that bad, but even if they double it the cost is still going to be fairly ridiculous.

It annoys me that Magians started with "go out and put in a bunch of work to improve your character" but is finishing up with "buy a bunch of stuff". It just seems like lazy game design to me.

And before someone says anything, I can afford to buy geodes, that quite obviously isn't the point.