Creating a powerful team for arena is about finding ways to make the group of characters more than the sum of their parts.
Bringing all heavy hitters is great if you get to go first, but if you don't have any defense and all characters with low HP, it's going to be tough to survive an onslaught in the first round if you lose the coin toss. Likewise, if you bring all characters that can take a beating but never really do damage, it's going to be tough to ever take out one of the opposing toons.
Good teams are usually a mixture of several of the classes of characters. A heavy hitter with a blocker and a healer can get you through a lot of battles. Add in someone that can revive dead toons and you're going to have a pretty strong team.
Alternatively, heavy hitters with high HP with a blocker and some shields can be brutal to try to plow through.
Some characters even seem like they're built for each other. Here are a few combinations that become bigger than either character, which will be useful not only for PVE, but also for PVP in some circumstances.
Blocker + damage avoidance. If you have someone on your team, such as one of the blockers we have listed on our site, and were to add in someone that either grants shields for damage types, has damage avoidance, grants invisibility, or even applies invincibility to the blocker, now it's going to be much tougher to knock out the blocker, which makes it even tougher to harm the rest of your team. Some examples would be Magus Lilith with Assassin Banshee, The Nomad and Set or even Steel, Fortune or Destiny talisman sets on any of the blocking characters.
Stunning combos. There are several one two punch combinations that can leave teams stunned. A couple of examples would be Iron Eddie and Assassin Demon Spawn or Beelzebub and Warrior Lilith. Of course, there are single characters that can stun entire teams like Horus or the Corrupt General, but the two character setups can typically do it more reliably. If you see one of those combinations, some Immunity or Angel talismans can become your best friend.
Damage scaling. Characters which grant charge to a team can really deliver a huge punch. Coupling a Warrior Child of the Damned, The Nomad and a Warrior Lilith can lead to some huge damage numbers. Reducing defensive stats can lead to some great numbers as well with abilities like DEF Down or Exhaust.
With this in mind, let's dig into who fits into each of these categories and why you might prefer one over another.