Act 4, 5 and 6 are nerfed and new accounts have easy (too easy) access to high-tier champs. You have not learn to play the game properly hence it feels difficult.For Act 6, you need to scout the nodes, think about your counters and how to play the fight; can you use parry, is using special giving opponent insane powers, can you hit into block, do you have an evade counter, etc etc.Edit: How did you managed 5.4.6 Ultron?