On October 15, the 18.4.2 patch that includes Battlegrounds balance updates will be released.
Heroes like Ragnaros the Firelord and Sulfuras will get nerfed, others like Chenvaala and Sindragosa get buffed.
Also, Minions like Deadly Spore saw changes.
Battlegrounds Hero Updates
» Removed Heroes
Bartendotron has been removed from the Battlegrounds Hero Pool.
» Ragnaros the Firelord
DIE, INSECTS!
Old: After you kill 20 enemy minions, get Sulfuras. → New: After you kill 25 enemy minions, get Sulfuras.
Sulfuras
Old: At the end of your turn, give your left and right-most minions +4/+4. → New: At the end of your turn, give your left and right-most minions +3/+3.
» Maiev Shadowsong
Imprison
Old: Make a minion in Bob’s Tavern Dormant. After 2 turns, get it with +1/+1. → New: Make a minion in Bob’s Tavern Dormant. After 2 turns, get it with +1 Attack.
» Chenvaala
Avalanche
Old: After you play 3 Elementals, reduce the cost of upgrading Bob’s Tavern by (2). → New: After you play 3 Elementals, reduce the cost of upgrading Bob’s Tavern by (3).
» Patchwerk
All Patched Up
Old: Start with 50 Health instead of 40. → New: Start with 55 Health instead of 40.
» Sindragosa
Stay Frosty
Old: At the end of your turn, Frozen minions get +1/+1. → New: At the end of your turn, Frozen minions get +2/+1.
» King Mukla
Bananarama
Now has a chance to give King Mukla a Big Banana that gives a minion +2/+2.
Battlegrounds Minion Updates
» Removed Minions
Whirlwind Tempest has been removed from the Battlegrounds minion pool.
Pogo-Hopper has been removed from the Battlegrounds minion pool.
Old: At the end of your turn, give your left-most minion +1 / +1 for each Elemental you played this turn. → New: At the end of your turn, give your left-most minion +1/+1. Repeat for each Elemental you played this turn.