This is the measure of the level of your Companion. All Companions start out with a max level of 5. You can further increase this level cap by spending Platinum. See table below for more info.

Each Companion has their own set of three unique Passives. Every time you level a Companion, the Passive gets better. Passives do not require any additional investment beyond raising the level cap of your Companion. The passive will unlock automatically when reaching levels 1, 25 & 75.

Each Companion has their own set of unique Abilities. You must spend Platinum to level your Abilities. You cannot level an Ability to a higher point than your Companion level. So, if your Companion is level 25, you can at most have level 25 on an Ability for that Companion. Abilities get stronger the more you level them up. Stronger abilities unlock as your Companion levels up.

The Platinum cost of Abilities goes up by +1 every 10 levels. ie: Level 1-10 = 1 Platinum per level, Level 11-20 = 2 Platinum per level, etc. Some abilities have cost multipliers built into them. So an ability with a 2x cost multiplier would start at 2 Platinum per level and go up by that.

You gain +5 Level Cap per upgrade.