Undead Traits: 100% fort, healed by negative energy, immune to positive energy. Cannot target yourself with necrotic touch, chill touch or inflict wounds spells. This makes self healing impossible (haven't tested with a friendly cleric casting mass inflict wounds though)
Wraith form: Duration 3 minutes, 5 minute cooldown. Grants undead traits. 25% incorporeal miss chance. Featherfall. +20 Move silently. Deals con damage on unarmed crits. I dont see a purpose for this yet... (maybe just stealth??) The healing immunity is a pretty large penalty for just 25% incorporeal...
Lich form: Duration 3 minutes, 5 minute cooldown. Grants undead traits. +4 con, +4 int +2 necromancy DC. Applies an inflict wound spell on unarmed attacks. Occasionally recives temporary hp when hit (appears to be 10% chance for 30 hp).