Ravos provides another Cleric tribal commander, something to use with Silverchase Fox to ruin the Theros block Gods, a way to recur some evoke creatures, and (the best option I saw) recurring token producers like Captain of the Watch and Cloudgoat Ranger
The Precon List Before we talk upgrades, let's take a look at the stock list to see what we're working with: A lot of folks say Hosts of Mordor is an unfocused pile of cards but this is just a poor shallow analysis of the deck: looking at the numbers indicate that it's pretty well-focused on Graveyard and Spellslinger: I count 27 Graveyard cards, counting any card that mills (Forbidden Alchemy), discards (The Balrog of Moria), reanimates (Extract from Darkness), or can be cast from the graveyard (Wake the Dragon)
This deck also features powerful removal and card draw
Unlock a variety of effects when character cards reaches a certain value are on the field
Easily the least exciting of the cycle, giving your team first strike isnt something to turn your nose up at
Vaevictis' pump effect can also be relevant, but poor Palladia gets the short end of the stick - she's just a very big, trample-y dragon