Wizard 3/Archivist 3/Mystic Theurge 9 Lich?

[atemu1234]

Running that as an NPC for my campaigns. Any tips?

[Kioras]

Well, as a 15th (EL 19) level character, a 17 CR creature it is a combo that looks better on paper then it will play.

You only have 6th(CL12) level spells, in both sets of spells, and you will still be action limited. Some early entry tricks would help things a little bit, but you would still have an issue with players.

It would be better to have a level 15(8th level spells) wizard lich, with a level 13(7th level spells) necropolitan archivist follower/minion, somewhat like the Xykon/Redcloak combination. The players would have a strong action economy advantage against such a single character, 2 will make them more cautious. A few dispels to rip off buffs, and they can go from there.

Not to mention 2 of them would be able to reliably handle more undead minions in combat, giving you even more things to annoy the players with.