In one of the tab on the left, I think it is the top one, click it and scroll down. You will find a list of hero abilities and what they do.

引用自 Azihar：

In one of the tab on the left, I think it is the top one, click it and scroll down. You will find a list of hero abilities and what they do.

Ah I see, so he provides a buff to my fighters' speed, durability, and damage while he's deployed.

Command tiers give a flat bonus to several stats - the strength (and stats being boosted) decided by their tier - whilst command traits like Fighter Commander give an additional buff (and sometimes debuff), sometimes limited to a select number of untis.

It's worth noting that when FoTR hits .5, the Command Tier system is going to be redone and revamped; not only will it take in more influence from a heroes rank, but the tiers will be expanding from 5 tiers to 11 (although you can technically hit 12). The bonuses for the lower ranks in .5 are smaller than the bonuses in .4, but the higher ranks are much more powerful than they used to be.

If you're curious how it's going to work out, I'd suggest booting up Rev and seeing how it works in there to better prepare for the update.