As of 2/29/2024, the Ranked Battle System has been overhauled and league limits for archons no longer exist. Read the Official Announcement here https://peakd.com/splinterlands/@splinterlands/splinterlands-ranked-battle-overhaul
What does leveling up an archon do?
Instead of gaining abilities and stats when leveled up, archons can call forth higher-level units at each new level. Increase the level of your archon by combining cards.
Unsure of where an archon falls? Click on an archon within the Splinterlands Market or your inventory. Next, locate the Stats tab. At Level 5, Bella Ratajowski is a Rare Life archon that can call forth Level 5 Rare Units.
Archon Level With Unit Interaction
If you are unable to use a Unit at the highest level available with a specific archon, you will need to increase the level of that archon by combining cards. A warning mark sign with the text will be shown on the affected Units.