[Jomar]

you only get mana increases post-200 on odd numbers. from there, it really varies on the amount per increase. to put it into perspective:
player x has 200 int, equipping a pure int item (no +mana) with the following amounts results in the mentioned increases at level 60
1-2=9 (+9 for +2 increase)
3-4=22 (+11 per +2 increase)
5-6=33 (+11 per +2 increase)
7-8=45 (+11.25 per +2 increase)
9-10=54 (+10.8 per +2 increase)
11-12=67 (+11.17 per +2 increase)
13-14=77 (+11 per +2 increase)
15-16=90 (+11.25 per +2 increase)
17-18=99 (+11 per +2 increase)
19-20=113 (+11.3 per +2 increase)
21-22=122 (+11.1 per +2 increase)
23-24=135 (+11.25 per +2 increase)
25-26=144 (+11.08 per +2 increase)
27-28=158 (+11.29 per +2 increase)
29-30=167 (+11.13 per +2 increase)
...and so on.

i've always thought that every even number post-200 here for int/wis being worthless was wonky, but i figured there was a reason for it being that way here if such a big thing wasn't being changed. i tried looking up evidence, but there were like 4 different formulas that people used to calculate post-200 int/wis prior to the soft cap raising up to 255 and so i just left it alone. it would be nice if this got changed though so casters and priests didn't have to balance their core stat on odd numbers all the time to get the most mana out of their items.