Overview
General
Pax Dei will sport an action based combat system that aims to be more strategic than reactive, so the decisions you make before combat (gearing up, knowing the weaknesses etc) are at least as important than the ones you make during combat. It won't be hotkey smashing and not super timing sensitive either as the goal is to make anticipation and reading the encounter more important than reaction speeds but there will be room for mastery.
Perspective
No matter if you are currently in combat or not, you are experiencing the game from a 3rd person perspective at all times.
Targeting system
There won't be tab-targeting. Combat will be action based and you chose the direction of your attacks.
As for spell-casting, here's a quote from the developer:
...we will offer different types of targeting, not just AoE, so yes you will be able to decide who to heal...
Player collision
Collision between players is active if both players are wielding a weapon in their hand. No collisions with empty hands or tools in hand.
Melee attacks
There will be attacks allowing you to swing melee weapons where directional combat is the main rule. Weapons are confirmed to have different attack rates and damage based on their weight/size, which is supposed to be part of the main strategy in combat.
Ranged attacks
Ranged attacks will be available. As for bow shots, they will need to be charged and physics will play a role on how the arrows perform.
Other attacks & spells
Other abilities have been mentioned to be available, most likely magic based. It was mentioned that some spells will require reagents.
Schools of Magic
When it comes to magic, the term "Schools of Magic" was mentioned. This implies multiple types of magic which probably will possess their own character skills that have to be trained.
Damage types & numbers
The specific damage types have not been revealed yet, but a developer mentioned that there are 8 different ones.
Various Schools of Magic will map to the different damage types, as well as other sources of damage (presumably melee & ranged).
It was mentioned that the game will show damage numbers and types in combat.
Stamina
Stamina is the "main currency" in combat. Most actions and abilities will use stamina. Running out of stamina will have meaningful (but not frustrating) consequences, which may be dire though. The system is said to allow some "leeway" in that regard though.