Only Story mode companions have a small background story. If your companion dies when facing a group of enemies, he will auto revive after you do, or after you eliminate the group of enemies around. As they reach max level cap, they cannot level up further. Max companion level is 70, same as your hero's. However, even when your companion unlocks all of their skills, they can level up and the in-game system will automatically add their base stats (amount based by each character). Each companion gives you one utility spell, and have other passive ones that unlock by his/her leveling up.

To start, you have only one slot for companions, but you can unlock another two slots for 75 and 350 gems each. You can find three of them in the first act of the game, the other four of them can be bought for 500 gems each at the Store page. I'm not talking about fixing Comps *solely* for the benefit of veteran players such as yourself.Companions are your only friends in the horrifying world of Mage and Minions. Remember, players don't start off at TL105. They're only an issue if they can't be gotten to, but 23.7fps makes up for that, and the only reason to hit them early is to free up the Comps who get married to them. Right now, my main Mage is at TL87 and 618K Damage, and healers are dust after a full Imm/Blizz/Sing rotation. Like I said, it's not like they can put a dent in high-level healers on their own. No matter what your dps.That's why I also mentioned the range, and also said 'generally.' My point is that in many cases, you'll have to clear out at least a huge chunk of the mob before you can give the healers the TLC they deserve, so it would be better if the Comps stick close to the player and support that effort instead of going off on their own little missions against the healers. At high trials, the bolded/italicized portion is untrue.

Best companions eternium