Hi! Just yesterday I opened 16 Gladius cases. And although I was trying to farm regular cards, I only got 2 legendary cards, 6 epic cards, and the rest were common and rare cards. While I couldn't level up any cards, I did accumulate a good number of common and rare cards. Since most Gladius cards are already at the top of the gold league, leveling them up is difficult. It's ultimately a long-term process.
!BBH