Hi all. My name is Jarvz, an avid gamer and strategist. The purpose of this guide is to illustrate basic combat mechanics and interactions as well as tips and tricks. I hope you find this guide useful and can use it to improve your play!

TLDR: Tons of Damage.

Status Effects are lingering effects on your character or enemies that show up as an icon next to their portait in and outside battle. Although a list of status effects can be found on the wiki [divinityoriginalsin2.wiki.fextralife.com], the interactions and scaling are not described.

• Damage statuses (poisoned/burning) scale off of character level and skill points (geomancy/pyrokinetic), respectively.
  
• The tooltip when hovering over a surface illustrates the impact damage (~half tick dmg) caused when walking through the damage surface when the surface is not buffed. As an example, casting fossil strike on a lantern does less fire damage damage because it does not consider your pyrokinetics.
  
• Damage statuses cannot critically hit.
  
• Fire/burning does not explode poisoned status.
  
• Flay skin does not reduce undead poison resist. Undead poison resist is always 200%.

Other Notes:

• Walking through a damage surface (fire/poison) causes 1/2 the tick value of the status effect per ~2 meters.
  
• Damage surface reactions also seem to do 1/2 the tick value on contact. As an example, if the fire tick damage is 140, a character standing in oil that becomes ignited will take 70 damage on ignition.
  
• Surfaces are replaced if another surface is placed on top of them.
  
• Surfaces that can be ignited can also be ignited by local light sources such as lanterns/ torches.
  
• Casting a surface modifying skill that breaks open a grenade applies the reaction. For example, casting fossil strike on a table with a firestorm grenade will explode the grenade and ignite the oil area immediately.
  
• Can fly over surfaces using wings (normal movement), as long as you do not stop in the surface.
  
• Blessed/Cursed versions last 2 turns.

Other Notes:

• Walking through a damage cloud (fire/poison) causes 1/2 the tick value of the status effect per ~2 meters.
  
• Damage cloud reactions also seem to do 1/2 the tick value on contact. As an example, if the fire tick damage is 140, a character standing in a poison cloud that becomes ignited will take 70 damage on ignition.
  
• Clouds can be condensed to surfaces via pressure spike, excluding fire/smoke which is removed.
  
• Clouds that can be ignited can also be ignited by local light sources such as lanterns/ torches.
  
• Blessed/Cursed versions last 2 turns.

• In order for magic to critically strike you need the talent "Savage Sortilege."
  
• Shielding abilities such as fortify and magic shell cannot critically shield.
  
• Healing spells such as restoration cannot critically heal, however, when applied to undead they can critically do damage, including their healing over time ticks!
  
• Burning/poisoned cannot critically hit. Including surface damage, cloud damage, and the damage over time status ticks.
  
• Poison cannot critically heal undead.

• Have 200% poison resistance, meaning that poison heals them. This resistance cannot increase nor decrease.
  
• Cannot bleed.
  
• Cannot be damaged by deathfog.
  
• Will cause people to attack if missing clothing while in skeleton form.
  
• Can be damaged by healing spells.
  
• Healing spells cause physical damage to undead.
  
• Can be critically damaged by healing spells, including their "heal" over time ticks.
  
• Do not require lockpicks, they use their fingers.
  
• Cannot critically heal from poison.

Damage Can be calculated with the following (Key):
B = Base damage (from weapon/spell)
CS = Combat skill % (warfare etc)
A = Attribute % (finesse etc)
W = Weapon Bonus % (single-handed etc)
M = Misc Bonus % (thick of the fight etc)
H = High Ground Bonus %
C = Crit Bonus %
AD = Ability Damage (see below)
TD = Total Damage (see below)

Formulas:
Ability Damage = B * ( 1 + CS/100 )
Total Damage = AD + ( AD * A/100 ) + (AD * ( W/100 + M/100 ))
Final Damage = TD * ( 1 + H/100) * ( 1 + C/100 )

Shield spells scale with level and respective skills (geomancy/hydrosophist).

Table below shows fortify/magic shell values per level:

Tips for DOS2 ranging from basic to advanced.
Some of these are extremely helpful.

• Undead can lockpick with their bony fingers, no need for lockpicks.
  
• Undead are immune to deathfog. (Can be useful in Act 3)
  
• Pressing shift reveals NPC vision areas for sneaking/starting fights.
  
• Pressing Alt while adventuring reveals items/ingredients lying around the world.
  
• Bedrolls can be used to heal out of combat. A bedroll has infinite uses.
  
• Zaikk's Talon can be used to turn normal health potion to poison ones.
  
• Sometimes when combining items you may need to split the item into separate stacks. You can split item stacks by holding shift and dragging the item to another slot in inventory.
  
• You can combine an ooze barrel with most weapons (sometimes even if they already have poison/other elements), adding poison damage and increasing their value for free. An ooze barrel has infinite uses. Wands cannot be buffed this way.
  
• Ooze barrels can also be combined with empty potion bottles, generating small poison potions. This does not increase the monetary value of the potion bottle.
  
• Teleporting objects such as crates/barrels over enemies does damage proportional to the weight within the crate/barrel.