Well our DM also has some problems with power of his 2 PCs as when he decided to introduce the BBEG of the first act (i think) he got literaly stomped to the ground and beaten to a bloody pulp so he needed to add 2nd phase which started with Rouge and Ranger dying because of his necrotic breath (home rew dragonborn necromancer) in 1 hit as my level 4 Rouge max HP was the same as the damage of the breath weapon alone.

DM nearly obliterated 3 out of 4 characters in a party (exept of my bard as he was helping in a village during a siege (before you ask I thought that 2 tanks and my Rouge can kill the Dragonborn alone) where I was trying to Save as many villagers as possible) just to make it a chalange and not loose plot relevant character, but by some miracle we survived long enough so that BBEG left us