Orcs

 Orcs are often the best choice for a new players first team. Orcs consist of a fairly strong team for tower and arena, for how easy they are to collect and have a clear progression on how you can improve the team as you level up and obtain harder to collect, more powerful heroes.

Core Team

Rantha- 

Rantha is your first key leader for the team. Her leadership provides pivotal passive healing for early progressions in the tower. Her bear friend serves as a nice round of tanking for the team when you are hit with a buff blocker or Tromgar is otherwise unavailable to taunt. It wont last much longer than that, but it serves its purpose. Her damage is not great, but functional. Rantha is eventually replaced by Zerra when she becomes available.

Runes: Rantha's best feature is the ability to summon her bear friend to take a few hits. This means that you want to focus on speed and health. The more speed she has the more opportunities to summon the bear, and the more health she has the more health the bear has and the more likely she survives to summon him again.

Artifacts: Again the most important thing for her is to survive to summon her bear as many times as possible. I would suggest using a health increasing artifact. Potency is useless, so for the offensive buff anything that increases damage will help a small degree. I dont yet see a 3rd effect that would give an item an edge over just having more health.

Tromgar- 

Tromgar is one of the strongest tanks in the game (top 2-3). When he taunts he also adds a counterattack to his taunt. This means he hits the targets back with his basic attack. His basic attack has a chance to stun the target. This means he often stuns a good portion of the opposing team costing them one of their turns. His third ability is a moderate heal on himself keeping him in the fight.

Runes: This is the hard part. You need Tromgar to survive as much as possible, so you want high armor or health. You also want potency, because this raises the chance to stun a great deal. Tenacity is good as well, because if he is stunned or gets hit with an ability or buff block he can be dead weight. My suggestion is to go full armor set runes. In the top left make sure your primary buff is Potency. 

An alternative rune set that is very popular in a Zerra heavy meta is to run full tenacity. Zerra's debuff will stop you from taunting the first turn, but if you resist it, you are free to taunt the most important round in the match. If Zerra isn't heavy yet in your meta, I wouldn't bother with this strategy. 

Artifacts:There is one artifact, made for Tromgar, that I cannot wait to get. It has the ability to give him taunt for 2 turns the first time he loses taunt. This is really good as it will let taunt likely last the entire combat. This artifact also has the two stats you want to find for Tromgar, Potency and Armor. If you cannot get this specific artifact, use one with those two abilities until you do.

Mortha-

Mortha fills the role of healing and does, well ok at it. She has one strong heal that is a little more than single target, but it has a long cool down. She has a second cooldown ability with a passive shield buff, that is fairly weak, but usable. Her primary ability is a weak attack. On the surface she seems kinda meh, but a well placed heal from her can often turn the tide in battle. 

Runes: The most important thing is that Rantha stays alive long enough to heal other members of the team. For this reason I suggest using health set runes. In the top right use a speed primary stat rune, because you want to cast as many heals as you can. Damage, when available should probably be the next priority to make her heal a little stronger.

Artifacts: Damage increase will increase the value of her heals and health or armor will help her survive. I don't see any key artifacts to look out for, so find one you like with those stats.

Maar-

Maar is all about dishing out as much damage as possible. He does this fairly well. I wouldn't say he is the best damage dealer on the team, but he definitely does his job well.

Runes: Crit is the name of the game here. Use all crit chance set pieces. Once again use speed in the top right (yes this is fairly standard). The main reason for high crit chance is that his secondary attack gets refreshed if it crits against 4+ targets. This happens often enough, if you run crit runes, to be a strong strategy.

Artifacts: I suggest running an artifact with an effect that increases damage when he crits. As for stats they all kinda do the same thing if you have high enough crit chance before the artifact is equipped.

Korkhrim-

Korkhrim is primarily a damage dealer, but unlike Maar it isn't as strait forward. He tends to focus more on disrupting his opponent while dealing a little less damage. At first he feels kinda weak in comparison, but he really comes into stride in later levels. His group stun should not be underestimated.

Runes: You want three things on Korkhrim, Potency, Speed, and Damage. I suggest focusing on the first two for your rune sets. Rune 4 speed and 2 potency. Potency primary and speed primary in your top corner runes, damage in your lower rune. Use as many speed, damage, and potency secondaries as you can. 

Artifact: I'd suggest a potency artifact as your attack stat and wont put much stock in the defensive stat. Alternatively, you could do damage as well and do just fine. There is one cool artifact that lets you use invisibility when you damage a single target. This effect makes it harder to target Korkhrim, which is great as it lets him focus on offence.

Upgrades

Zerra-

Zerra is one of my favorite damage dealers in the game. She is absolutely game warping with a fantastic leadership ability and some heavy damage output. The debuffs she adds to her attacks simply change the flow of battle. 

Whether you use her or not, you need to understand how her leadership ability works for when you face her. She puts a handful of debuffs on each member of the opposing team before the battle starts. They lower damage, lower attack, make debuffs easier to land, and probably most important stop buffs for that turn. So, if you run into her, plan to not cast your buffs on the first turn including taunt. (high tenacity gets around this sometimes)

Runes: I would suggest 4 speed set pieces and 2 potency. Potency should be your top left corner rune as well and speed the top right. After that, increase damage whenever you can. 

Artifacts: Increase either damage or potency, depending how comfortable with her current potency.  I would suggest armor or life steal as the defensive ability. Try to find an effect that has a long term advantage. I use one that has a chance to remove a debuff each turn.

Replace: I would replace Rantha with Zerra. The reason for this is Rantha's best role on the team is as the leader. Once you take that away (as Zerra should lead most of the time now) her role on the team is very diminished. 

Hardorc- 

Hardorc is a debuffing machine. Unfortunately, I have not unlocked this character enough to fully test him out yet. What I can say is that he's really annoying to play against. 

Runes: You want him to take as many turns as possible. So go full speed. Next you want potency to land the debuffs. After that damage is fills the rest.

Artifacts: Again pump potency. Health or armor are good for the defensive stat. He gets a buff from his artifact, the horn of war, so it may be best to find one of those with a secondary ability you like.

Replace: This one is hard, but I think it boils down to two options. If you really feel you need Mortha's heals, replace Maar. Maar's damage is great, but debuffs are typically better. I would keep Korkhrim over Maar due to his stun alone. That being said, sometimes the best defense is a strong offence. Aside from the one key heal, Hardorc is probably a better support character than Rantha. I'd probably replace Rantha at this point and try to win quickly.

Mor'doom

Mor'doom doesn't belong on this list to be frank. If you are to the point that you have unlocked Mor'doom, you probably don't need a pure orc team anymore as you have probably unlocked Sol as well. If not he will fit anywhere on your team. 

Runes: Go for speed first followed by potency. This is starting to seem like a trend, but it is what works on hard hitting debuffing characters that you want to take alot of turns. Alternatively, you could take advantage of the fact that players are likely to target MD first in this group and go with high health. This has the secondary effect of high health demon minions. I'd still suggest speed/potency though.

Artifact: You want damage as your primary attack stat. That being said I will be looking for something that gives him invisibility or some other cool secondary effect.

Replace: Replace Maar or Korkhrim. They are damage dealers he is a stronger damage dealer. It's an easy trade.

Dieslrog- 

Dieslrog is not currently a viable character, do not use him. 

Non Orcs

Outside of the legendary events you do not need to stick to single racial teams. While you could take members of this team to other teams, I don't see much advantage of adding to this team. There is no standout character that would be amazing on the mostly orc team. However there is nothing limiting you to Orcs either maybe you want to run Zerra and Tromgar along side 3 non orc characters, there are no limits here.