And, if you're just getting started with Magic's digital younger sibling, try out our guides to MTG Arena codes and the best MTG arena decks to get the ball rolling.
You get an emblem with "Pay 2 life: Add one mana of any color" and "At the beginning of your upkeep, you draw a card and you lose 1 life." If an effect would cause you to gain life past your maximum life total, you won't gain any life above your maximum life total
Understanding the phasing allow you to implement clever tricks
Sidisi might be Commander-eligible, but it's better in the 99 of a deck
For example, if you somehow used Souls of the Lost to craft Mastercraft Raptor (perhaps because it became a copy of a Dinosaur), its power while in exile is equal to the number of permanent cards in your graveyard, and Mastercraft Raptor's power will change as the number of permanent cards in your graveyard changes