I'd put the 18 in your intelligence, and the 17's in your char and Strength.

The Warmage get's bonus damage based off of Inteligince. But since you don't get retro skill points for raising your intelligence later you want to put your best even number stat there and leave it alone.

Str and Char can both get bonuses when you pump them up later as you level. so put them both at 17 and then bump them up at 4th and 8th as you need to.

As for the rest of your stats it doesn't matter. They're all good. Plan it out so your stat increases even out the odd stats at later levels.

Try this array.

17, 15, 14, 18, 13, 17

The Warmage and Palladin both get good will saves so you're fine there. The palladin also get's a good Fort save so once again you're fine. Neither get good Ref. Also the Warmage has a lot of range touch spells and it will limit you to lighter armor so the extra dex will help out in more places.

Use your stat increases to bump up Dex/Char/Str/Wis/Whatever for the last one. That way they'll all even out. Find items to bump up your charusma more.

Take advantage of your multiple stat goodness by Gishing the build.