Apparently you can't deep splash an arcane.
Chain missiles no longer gives 10 missiles regardless of caster lvl. Wiki is wrong. I don't know when this changed, but its not working for me now on a test new 7 wizard.
No chain missiles means no shiradi, no shiradi means you have to have powerful spells, which a deep splash won't have.
Edit: I only meant to say that to me it logically appears that you can't deep splash an arcane to good effect. A PSA for those who were considering something other than 18/2 or pure 20.
I'll be the first to admit a deep splash would allow arcane versions of the juggernaut. Self contained healing, spell dps, trapping, ccing characters with no weakness. But they wouldn't have any exceptional strengths either.