I think the Illusion spell school could use some love, especially for Bard builds. Here are a few suggestions on PnP spells that could be moved to DDO.
1. Mirror Image - This would be an awesome damage mitigator for caster classes. Initially, it is a high miss chance that decreases as the caster is missed. It could be implemented as written for PnP. Caster gets X images, which gives them a miss chance of (X/X+1*100)%. Each time they are missed, reduce X by 1. X = 1d4 + 1/3 caster levels (max 8).
2. Silent Image, Minor Image, Major Image - I think these could be done in three different flavors.
A. Distraction - The image works exactly like the Noisemaker traps. Creatures in the area are drawn to the image if they fail a Will save.
B. Fascination - The image fascinates creatures in the area, if they fail a will save. (similar to Hypnotic pattern).
C. Aggravation - The image aggravates creatures, causing them to attack it if they fail a Will save. Once 'hit' the image dissipates. Could be used in combat as a minor Intimidate.
3. Disguise Self - Increase or decrease your threat generation. Optionally, provide a bonus to some skill checks (bluff, diplomacy, etc.).
4. Halucinatory Terrain - Creatures passing through the area are crippled or have slowed movement (similar to Entangle or Spike Growth).
5. Mislead - Crates an image of you that intimidates targets and puts invisibility on you. This is a great one to use in situations where you need to get away from several mobs that you have pulled aggro for.