500k eh?
Snowglobe Staff
Scarab Ring
Obsidian Dagger / Scarab Ring (depends on how much you value defense over offense)
Illusens Earth Potion
Bronze/Red/Blue Scorchstone (Blue is probably out of your range)
Downsize!
Leaf Shield
Bomb such as Sticky Snowball
Cloudy Wand of Storms or Frozen Wand of Crystals would rock instead of the Dagger/second Scarab Ring to pair up with Scarab Ring as a second dual duty weapon, if you can find one for 300k or under, get it.
As for basic strategies, I've found a few work for war opponenets.
a. Typical freezebombing:
Snowglobe staff + leaf shield/downsize/scorchstone/scarab ring (depending on your position, the point is second wep should be defense, not attack) until freeze then use Illusens Earth Potion + a second strong offensive weapon with fierce.
b. Wear down
I used this in the last war, and scraped at least 500 points than I could have had, it's dead useful. Use two dual duty weapons (such as scarab ring or one of the wands) along with your species attack. This has the advantage of doing constant damage without any loss of attack or defense (0 percent boost to attack, 0 percent loss to defense compaired with 20-30 percent gain to attack and 20-30 percent loss if you use a move like fierce) along with 4-6 additional icons of damage from your species attack. For Krawk, that would be "Krawk Death Stare".
c. KAMAKAZE!
This one's fun. Just use your strongest weapons with fierce on the first attack. Don't like how it turns out? Go back and restart the battle, use a healing item + defend until you are full health then go back and restart again.
Also, having burrow/sink is a MUST. Get the faerie ability burrow immediatly if you are level 21ish by using a bunch of Bottled Earth Faeries until you get it.