Over time, crusader tags have gone from being really minor things that only affect a couple crusader upgrades to a core mechanic that affects a ton of upgrades, not to mention missions. It has gone from information that is only relevant to players who use certain niche formations to information that is relevant to everyone, and absolutely critical for a growing number of crusaders/formations.

And yet, unless I'm missing something, there is no direct way to see this info in-game! You can identify a crusader with a formation upgrade that only affects a certain tag, then continually swap out crusaders from other slots and mouse over the one with the formation upgrade to see who his upgrade is buffing. You can wait till you have no active missions, then find a mission that wants a crusader of a given tag, then temporarily toggle the option to show crusaders currently in your formation, then scroll through the list to see which crusaders show the icon for that tag...

...But both of those workarounds are a royal pain (pun intended), and there's no guarantee that you'll have a crusader with the right tag-based formation upgrade or a mission asking for the tag you're interested in. Even in the best case, they involve taking a couple minutes to do something tedious instead of actually playing the game. IMHO, given how important these tags have become, it is LONG past time to add that information to the UI in a more sensible way.

Off the top of my head, my suggestion would be to add a mouseover tooltip for each crusader's portrait on the leftmost tab of the main interface (the one with a sword icon, where you go to unlock and level up your crusaders). There are countless other places this info could be added that would be unobtrusive but still relatively convenient. As it stands, I mostly ignore crusaders whose upgrades depend on these tags. I'm sure I'm not the first one to bring this up, but we keep getting new crusaders with tag-dependent upgrades and we still don't have tags displayed directly in the UI, so... Pretty please, with cherries on top?

"add a mouseover tooltip for each crusader's portrait " - THAT would be EXTREMELY USEFUL for planning and allocating crusaders for missions - considering the various mission crusader requirements, completion times, and risks/rewards.

This issue is one of the few where I find mobile to be better. Since on mobile all of a crusaders tags are displayed on the Missions screen regardless of what the mission calls for. It would be great if that feature was carried over into the PC version.