Hi. Got some ideas. Here they are:

Character creation:
1. Add an option to choose body-type for character creation screen. It's bad to have only one option. It will be so cool to have tough barbarian/warrior/paladin instead of...this one we have now.

Miscellaneous:
1. Add cinematic for jumping critical hit.
2. Add item sets for classes which can be upgraded.
3. Add an option to re-color armor and weapons hilts.
4. Add unique models for unique items.
5. Add an option to customize armor and weapons: add damaging effects (poison/fire/lightning/ice and etc.) for weapons and same resistance effects for armor.

Classes
Hunter:
1. Add "Piercing shot" ability for Hunter subclass.
Explanation: Hunter releases special arrow that pierces first target and deals damage to a second target that is behind the first one (in line). First target takes full damage and "bleed effect", the second one - just full damage without "bleed effect". Can be activated 2 times per Long Rest.
2. Add "Silencing Shot" ability for Hunter subclass.
Explanation: Hunter releases special arrow that silences target. Can be activated 2 times per Short Rest.

Barbarian:
1. Add "Rampage" ability for Berserker subclass.
Explanation: Barbarian makes whirlwind strike dealing damage and knocking targets prone. Can be activated 2 times per Long Rest.
Or: Barbarian begins to whirl and then run over (whirling run) a short distance dealing damage and places "bleed effect" on every damaged target. Can be activated 2 times per Long Rest.
2. Add "Blind Rage" ability to Berserker subclass.
Explanation: Berserker strikes multiply times with low accuracy one target. Can be activated 2 times per Short Rest.
3. Add "Leaping strike" for Barbarian class.
Explanation: Barbarian leaps on targeted area dealing AoE damage. Has a chance to knock targets prone. Ability can be activated 2 times per Short Rest.

Rogue:
1. Add "Shadow Assault" ability.
Explanation: Rogue teleports from target to target 3 times dealing damage and poisoning them. Requires Stealth. Ability will be interrupted if Rogue missed. Can be activated 2 times per Long Rest.
2. Add "Throw dagger" ability.
Explanation: Rogue throws dagger that deals damage and places "poison" and "root" effects on target. Requires simple dagger in inventory. Can be activated 2 times per Short Rest.
3. Add "Exposed" ability.
Explanation: Rogue has +30% dodge chance and has +30% critical chance for 2 turns. Requires 50% or less HP. Can be activated 2 times per Long Rest.

Fighter:
1. Add "Readiness" ability.
Explanation: Fighter takes defensive stance taking 50% less damage from all sources except "magic" damage and parrying any melee attack dealing -30% less damage to attacker. While in that stance Fighter can't attack or move. Can be activated 2 times per Short Rest.
2. Add "Warbringer" ability.
Explanation: Fighter charges to single target dealing cone damage and places "bleed" effect on damaged targets. Requires non-light weapons. Can be activated 2 times per Long Rest.

Paladin:
1. Add "Exorcist Aura" spell.
Explanation: Paladin activates special ability which infuses Paladin with light (as Light cantrip spell) and deals low radiant damage to nearby fey/fiends/undead in a small radius for 2 turns. Each character's level increases its radius and damage. This spell can be activated 2 times per Long Rest.
2. Add "Avenger" spell.
Explanation: Paladin casts spell that blinds nearby enemies in a small radius and gives Paladin +50% critical chance for 1 turn. This spell will be automatically activated free (has no spell cost) if companion downed. Spell can be activated free 1 time per Short Rest.

P.S.: Abilities/spells names are for example.