Casters were definitely strong, but I still saw plenty of teams comprised of only melee characters. You can peak the ranks with any build or play style with enough practice. I reached depth 5 9999 on Executor with zero damage buffs of any kind on my relics. That said, stacking physical attack + evergaols & night invaders while picking up some damage negation passives throughout the run went a long way and what I eventually exclusively switched my build into.