The unit's name is pronounced "speh-DOO," rhyming with "skiddoo" owing to an interaction Rob had with a fan who pronounced it this way at GenCon 2012. They receive a special stack bonus if they number exactly 23.
First Appearance: TBFGK 1
Spidews have been used as mounts by Gobwins, Hobgobwin Knights, and Men and Uncroaked Warlords.
Possible special attack bonus for a stack of 23 may have something to do with a fear effect.
Can also be used on their own, without a rider.Erf-b1-p025
Real World References
In 'The Glory and the Dream: A Narrative on American History' by William Manchester, college people of the thirties on departure would say "Twenty-three skiddoo...".
"Skiddoo" means "to depart", and was possibly derived from "skedaddle", meaning "to flee in a panic".