===== D&D Core Mechanic=====

The D&D core mechanic is:
  -roll d20
  -add or subtract modifiers

The modifiers are really the core, the d20 is just the randomizer!

Modifiers come in several "flavors" (but they are really all the same)
  *Attribute bonuses
  *Skills and proficiencies
  *Attack Bonuses
  *Saving Throws

===Combat===
  *Initiative is just a d20 modifier. Highest roll goes first, and sticks for whole encounter
  *Take turns - Action + Move (+ bonus actions)
    * Attack, Cast, Dash, Disengage, Dodge, Help, Hide, Use Item, Search, Ready
  * Reaction (1 per round) 
    * including Opportunity Attack (voided by Disengage)
  * Attack (d20+ATK Mod) >= Armor Class == hit
    * roll Damage
    * NO Saving Throws on Attacks, attack go against AC
  * SOME spells are automatic (no ATK roll) but do offer Saving Throw