18 starting + 5 levels + 11 gear (epic diabolist 7, rakhir +1 and +2 exceptional, litany +1 profane), +4 enhancements (wizard + human), +2 ship, +2 yugo, +2 capstone, +2 tome.
= 46 int, easily maintained, gets you an int modifier of +18.
That gets our DC before other modifiers to 10 + 9 + 18 = 37
Now lets add wizard past life, focus and greater focus feats, greater focus item, archmage enhancements for main school. That's a total of 1 + 2 + 2 +2 = 7
So that's 44 dc in one school for an archmage. Add +1 dc from +4 int tome, +1 dc from completionist and you'll have 46 dc.
<edit> As a side note, since my secondary school is conjuration and epic Diabolist gives epic conjuration focus, my conju dc is 43 so only one point behind main school. Now I just need to do some cleric past lives to get +3 conju dc for even better webs
Full abishai cookie set gives +4 to all stats iirc, so that's +2 dc, then you have phiarlan, deneith and store pots so it's possible to get your int pretty high in the short term. I don't use any of those though so I don't really know too much about them, I know they're kinda difficult to get (except store pots if you buy them
). Some players do use all of those in speed runs etc, but I've never felt the need for that.
Hope that helps