I thought it might be fun to start a community driven guide to each character. The goal is to provide basic and advanced strategies , as well as counters for those strategies. While I'm sure many of these ideas have been discussed elsewhere, the goal with these threads will be to gather links and try to put everything in one easy source. That said, I am hardly an expert on any of the characters, and I strongly encourage others to add their own input.
Legacy
Legacy is a versatile character who can serve as a token generator for himself and his team, a guardian for his less durable allies, a melee striker, or a hybrid of two roles.
Token Generation Legacy: This is probably the most obvious Legacy build. By running Galvanize and Inspiring Presence, Legacy can hand out quite a few Attack +1 tokens and can even throw in a few Defense +1 tokens when necessary. Token generating legacy can be countered a couple of ways. The obvious, and most effective counter is Baron Blade's Devious Disrupter. However a second counter would be to use a character such as Citizen Dawn paired with Citizens Blood, Sweat & Tears to generate -1 tokens to negate corresponding +1 tokens.
Guardian Legacy: By running Danger Sense and Heroic Interception, Legacy can switch places with his less durable teammates and protect them from attack. With his high health, large pool of defense die, and Danger Sense's auto block, Legacy can absorb quite a beating without succumbing to incapacitation. The best way to counter this strategy is to use forced movement to break Legacy's line of sight to his allies or somply pile on the damage to K.O. LEgacy.
Melee Striker Legacy: To be most effective with this strategy, you need to have the promotional card Flying Smash. Without it, Legacy's low action pool can sometimes hamstring his ability to get into the fight. To be most effective you must assess how many targets you can attack and how far you need to travel. If you cannot reach your target with a move/sprint, you will likely want to arm Legacy with Surge of Strength and Flying Smash. If you can attack multiple targets, you may also want to use Surge of Strength and Flying Smash. However, if you can preserve your move, save your attack +1 counters for a Thokk, as you will get more bang for your buck with its higher hit percentage. Finally, if your will only be able to attack one target arm Surge of Strength and Inspiring Presence to load up on attck +1 tokens for a massive 6+ die Thokk. The law of averages suggests you will get 5 hits on six die Thokk which should overwhelm most defenses to get some damage through. To counter striker Legacy, keep your distance to capitalize on his low action pool, try to avoid tight formations where flying smash's radius one can hit multiple targets, and use elevation to make it dificult for Legacy to score hits. (editted to reflect the wisdom of the debate below)