[Endoperez]

Chainmail of Displacement (automatic Mirror Image AND +3 def) and Boots of Quickness (Quickenss grants +3 att, 3 def) will increase the defence even further.

IIRC, Swords of Quickness increase defence just as well as Ice Swords, and also grant twice as many attacks.

If you want protective gear, Starshine Skullcap (S2, boosts Astral magic and magic resistance) is much better than Horror Helmet against Doom Horrors.