Emerald Robe

Every gem robe does the same job in the shirt slot and they differ only in how much magic damage they carry. Emerald lands in the middle of that run, which makes it a fine placeholder while you keep digging for a better gem but not something to plan a build around.

The set bonus lives on the headwear, not the robe. Wizard Hat for critical strikes, Magic Hat for the bigger mana pool. Pants are irrelevant to the bonus, so wear whatever has the most defense on it.

Wearing any gem robe without a Wizard Hat sharply raises how often Tim spawns underground. If the hat is the piece you are missing, put the robe on before a caving trip and let him come find you.