Fair enough, wave 30 is basically endgame for the top 1%. But as far as my current build goes I'd think that this would be enough for T16 rare reds but it's not. I've got spell suppression, max resists (except for chaos), capped block, and decent phys reduction through armour and charges on hit. What am I missing?

I'm not following a guide. I threw this one together myself in an effort to better understand the systems underpinning the game. If this won't get to wave 30, what will?

After that, I’d question the choice of using a staff. Cold iron point + shield for example would be way more damage and way more defensive.

No reason other than I thought it would be fine.

And there’s a ton of unallocated 2 point jewel sockets.

What kind of jewels should I be using with this build?