Mirby had that as well, and I believe she said it increased the level limit for the card from 40 to 45.I'm going to have to make a conscious effort not to play this all day. DX This is like the first time I played Civ V.
By the way, does anyone know what Limit Cut in the card upgrade screen? (For example, using Cid on Cid shows "Limit Cut" where other cards might say EXP^)