>>61750372All Enemies Maximum Health decreased by 30%.
In comparison to Tactician, where enemies have almost twice (x1.9) as much max HP as Explorer enemies.
Party characters receive a 100% bonus to hit points.
Items purchased from a merchant are at a 20% discount.
All characters (including enemies) proficiency bonuses are increased by 2.
Some turn-limited combat gives you additional turns making the encounter easier.
Iron Throne is an example of this where you'll be given 6 rounds to solve the problem rather than 5 rounds at the other difficulty settings.
Multiclassing is not allowed on Explorer difficulty. Multiclass levels previously gained will stay if the difficulty is lowered to Explorer.
This makes the Jack of All Trades achievement (multiclass into all the 12 classes on a single character) unobtainable.