* Scoundrel Explorer: Monster Hunter is quite the skill. If you are a Goblin Scoundrel Explorer you can sneak attack everything
* Warrior Action Surge: While it's the Fighter key feature in D&D I find it kind of boring. Once you use (or waste it) in a combat that's it. My suggestion is adding a resource (Stamina?!) and a small list features you can use by spending the resource similar to D&D Monk Ki feature but Warrior oriented: maintain forced march, use a Bonus Action to make a single attack, resist Exhaustion, block an attack (shield or parry with a weapon), etc.
I love Symbaroum original ruleset, but I really enjoyed to see Symbaroum 5E flavour. It's a refreshing feel to 5E classes.