Sol, Advocate Eternal is a mythic Legendary Creature — Dragon Angel card from 2018 Heroes of the Realm (PH18), collector number 3. Current market price: $1.89, TCGplayer market prices via Scryfall.
Legendary partner (You can have two commanders if this is one of them. The other one is promoted to legendary.) Flying, vigilance Teamwork — Whenever you attack or block with both Sol, Advocate Eternal and its partner, support 4 and investigate four times.