The mechanics here are paraphrased or altered from the D&D 5e SRD, found here, for official rules see here (TODO: put amazon link?)
One of the first things you will do in Season of Arena is create a character. You'll be able to customize certain aspects of your character, including the following:
Abilities are Strength, Dexterity, Constitution, Intelligence, Wisdom, and Charisma. These are used to resolve conflicts between characters, or attempts at actions. For example, a character might attempt to grapple another character, causing a strength contest to take place. A dice is rolled for each character, and added to the strength bonus do determine the winner. Abilities also affect other stats, like effectiveness at avoiding certain types of dangers. At character creation, you are allowed to allocate a certain number of points to your abilities.
Combat take place on maps, which is broken into a grid of cells, each representing a 5-foot square of terrain.
At the start of combat, character turn order is decided by sorting characters by a value called initiative, which is based on dexterity and mostly chance. Characters are ordered on a cue (shown on the right in the HUD), where enemy names are written in red, and allies in green. The cue will only show characters that one of the player's characters or allies can see. If a character is out of sight, it is not shown on the cue.
Characters each take their turn. On a turn, characters can move and do 1 of each of the following: 1 action, 1 bonus action, and 1 interaction. Of course, characters can also just choose the "Wait" action, ending their turn early regardless.
Whichever side satisfies their victory conditions, or eliminates all enemies first wins the arena match.
On your turn, you can move up to your speed before, in-between, or after actions. Your base speed is determined by your race, and is typically 30ft (6 squares). A deviation from the official rules, is that you cannot move or melee attack diagonal squares.
Characters project vision up to a certain distance, which is used to spot enemies. When enemies aren't seen, their actions aren't logged for the player to see, and their actions are not animated.
There are many actions that characters might perform on the battlefield. Here are a few examples:
Bonus actions are usually given by special circumstances. Here are two examples:
Interactions can be taken to pick up, put down, or equip items. Drinking potions is also considered an interaction. Interactions can be used in place of regular actions if an action has already been taken this turn. For example, you can pick up an item from the ground, and equip it, but this would consume your action for the turn.