Hope you guys doing well. Ronan in the Battlerealm Under Siege (uncollected) is a pain to fight. Power gain, energy damage, unblockable specials, stun immunity, etc.. are the annoying buffs added to that node. However, just found a video created by Jason Voorhees that shows you the trick to defeating Ronan. Watch the video for more detail.
Best Champions to use against Ronan in Battlerealm Under Siege event