Critical hits and Fumbles
On any attack roll a natural (on the die, no modifiers) 20 is a critical hit and a 1 is a fumble. A second unmodified roll is made to determine the extent of the critical hit or fumble with higher being better and lower being worse. Another 20 on a critical hit or 1 on a fumble explodes (roll again) making the results more extreme.
HP in combat
Damage dealt to characters is described in detail but not in numbers. A character can use an action to check their injuries and get their current HPs.
In most cases the affects of Magic Items must be discovered through research, magic or experimentation.
Warlocks get four times their known cantrips per short rest
Everyone else gets twice their known cantrips per long rest including bonus cantrips from race and class. In lower magic game everyone half as many.
Default Cantrips known at first level from the PHB
Bard, Druid, Warlock – 2
Cleric, Wizard – 3
Sorcerer – 4
Wild Magic affects scale based on the level of the spell including Cantrips. Wild Magic checks must be rolled when using Cantrips as well as higher level spells.
Resting and Healing:
There are two types of rests a character can take, a short rest (1 hour) and a long rest (8 hours). Someone can only benefit from one long rest in a 24 hour period. A character can take more than one short rest in a 24 hour period but can only gain the same benefit from a short rest once in a 24 hour period such as a warlock regaining spells or a class features like a fighters second wind. A character can always used HD to regain HP after a short rest if they have any available.
After a long rest a character recovers half their HD rounded up. They can spend them after a short or long rest to recover HP which is considered their natural healing.
Healing Herbs can be harvested in parts of the world, when they are processed to make a healing past and applied with Medicine (DC 10) they can give an extra HD on a long rest.
Death Saves and Stabilization :
DC 15 Wisdom Medicine check to stabilize someone who is dying. DC 10 with Healers Kit and advantage on the check.
Failed death saves do not reset until after a long rest.
Know Beast Shapes:
Starting with 3 at 2nd level and +1/level after.
Nothing smaller than a Rat, crab or small bird.
Learning a new Beast Shape:
To learn a new best shape the druid must spend 24 hours living with a wild beast in its natural environment. It can be difficult to find animals which will allow the druid to live among them for this time. This can be aided by magical means such as animal friendship. After 24 hours the druid must make an animal handling (Wis) check with the DC 10 + the animals CR. If the check succeeds the druid can begin crafting a magical effigy of the creature. This must be made from something from the animals lair or the area where they live and it must resemble something about the beast. An appropriate crafting check must be made to complete the effigy. The DC 10 + the animals CR and takes one day to complete. If the druid uses tools they are proficiency with they can add their proficiency bonus to the role. If they use a part of animal they have an advantage on the role, examples of usable parts are fur, bone, teeth or horn. If the check is failed the materials are destroyed but the druid can try again after a long rest. If the effigy is ever lost or destroyed the druid cannot use this best shape until they make a new effigy with the same requirements. They do not need to repeat the first step of the process again. A new Beast Shape can be learned at anytime but a druid can only have a number of effigies up to their max known Beast Shapes.