With the patch 60352, the information about the Boss Battle Royale 3 Tavern Brawl has been released. Feel free to spoil yourself if you want to get a preview of the Heros and Powers.
Extract Aventure: TB_BBR3 - from patch: 60352
Heros & Powers
HERO:Hagatha the Vengeful (SHAMAN) - PV:30 - null HERO POWER: Swampqueen's Touch - Cost:2 - Hero Power Transform a friendly minion into one that costs 1-3 more. HERO:Rotwing (HUNTER) - PV:30 - null HERO POWER: Rot Aura - Cost:1 - Hero Power Trigger ALL Deathrattle effects. HERO:Lich Baz'hial (MAGE) - PV:15 - Baz'hial has cheated death. She also cheats at cards. HERO POWER: Lich's Phylactery - Cost:0 - Hero Power Restore $20 Health to your Hero. Reduce by 1 for every friendly minion that dies. HERO POWER: Broken Phylactery - Cost:0 - Passive Hero Power You take double damage from fatigue. HERO:Dr. Boom (WARRIOR) - PV:30 - null HERO POWER: SUMMON THE BOTS! - Cost:2 - Hero Power Add a random Boomlabs Mech to your hand. HERO:Kriziki the Winged (PRIEST) - PV:30 - null HERO POWER: Wings of Rebirth - Cost:2 - Hero Power Give a minion Reborn and 'Can't be targeted by spells or Hero Powers.' HERO:Baduu Prime (ROGUE) - PV:30 - null HERO POWER: Corrupted by Rust - Cost:0 - Passive Hero Power After you play a minion, give it Stealth or Poisonous. HERO:Cenarius (DRUID) - PV:30 - null HERO POWER: Nature's Grasp - Cost:2 - Hero Power Summon a 2/2 Treant with Taunt. HERO:Mecha-Jaraxxus (WARLOCK) - PV:30 - With rage and rust, he has been rebuilt! HERO:White King (NEUTRAL) - PV:30 - null HERO POWER: Castle - Cost:2 - Hero Power Discover a chess piece. HERO:Illidan Stormrage (DEMONHUNTER) - PV:30 - The Lord of Outland is looking forward to a rematch! HERO POWER: Burning Rage - Cost:0 - Passive Hero Power After your hero attacks, deal $1 damage to all enemies. HERO:Mother Shahraz (WARRIOR) - PV:30 - null HERO POWER: Parry and Riposte - Cost:0 - Passive Hero Power The first time you are damaged each turn, prevent it and counterattack!