Staff of Reverie, Manafont robe, and Iarumas
I haven't seen discussion on this yet, so I ran some quick numbers on my 122 mana Iarumas - with the assumption that mana pool amount isn't an outlier - and found if you have the staff of Reverie and Manafont robe equipped you get 2 extra level 1 Tzalik charges (6->8). Either the Staff or robe alone also gives an extra level 3 Tzalik (2->3), and because it's MAtk focused you can carry a different weapon for physical attack damage.
I'm wondering if this staff/robe combo is now best in slot for Iarumas. You'll likely sacrifice some MAtk in a +15/20 ebonsteel tier staff for a +10, but you get 30% more nukes per rest. If you have level 3 Tzalik, you could also mix in a full cost cast to optimize your mana usage.