Extus, Oriq Overlord
Legendary Creature — Human Warlock
Double strike
Magecraft — Whenever you cast or copy an instant or sorcery spell, return target nonlegendary creature card from your graveyard to your hand.
"Join me for the dawn of a new age."
Awaken the Blood Avatar
Sorcery
As an additional cost to cast this spell, you may sacrifice any number of creatures. This spell costs 
less to cast for each creature sacrificed this way.
Each opponent sacrifices a creature of their choice. Create a 3/6 black and red Avatar creature token with haste and "Whenever this token attacks, it deals 3 damage to each opponent." and "Whenever this token attacks, it deals 3 damage to each opponent."
Chase Stone
Rulings
If an effect creates multiple copies of an instant or sorcery spell, magecraft abilities trigger once for each copy created by the effect.
(wotc • 2021-04-16)
The Blood Avatar will be awakened even if no player has creatures to sacrifice when it resolves.
(wotc • 2021-04-16)
Awaken the Blood Avatar’s first ability can’t reduce its cost below {B}{R}. However, you can sacrifice any number of creatures, even if they won’t reduce its cost any further.
(wotc • 2021-04-16)
Each magecraft ability has a different effect, although they all have the same trigger condition, whenever you cast or copy an instant or sorcery spell.
(wotc • 2021-04-16)
For example, if you control Archmage Emeritus and cast an instant or sorcery spell, Archmage Emeritus’s magecraft ability will trigger and you will draw a card.
(wotc • 2021-04-16)
Some effects instruct you to copy an instant or sorcery card in a zone other than the stack. These copies do not cause magecraft abilities to trigger. However, most effects that do this also allow you to cast the copy, and casting the copy will cause magecraft abilities to trigger.
(wotc • 2021-04-16)
If an effect creates a copy of an instant or sorcery spell, this will also cause the magecraft ability to trigger.
(wotc • 2021-04-16)
As Awaken the Blood Avatar resolves, first the next opponent in turn order (or, if it’s an opponent’s turn, the opponent whose turn it is) chooses a creature they control, then each other opponent in turn order does the same knowing the choices made before them. Then all the chosen creatures are sacrificed at the same time.
(wotc • 2021-04-16)
Returning a nonlegendary creature card is not optional. If there is at least one in your graveyard, you must target it with the magecraft ability.
(wotc • 2021-04-16)
Include any additional costs to cast Awaken the Blood Avatar before applying its own cost reduction. For example, if Extus is your commander, and an additional cost of {6} applies from the “commander tax,” you may cast Awaken the Blood Avatar by sacrificing four creatures and paying {4}{B}{R}.
(wotc • 2021-04-16)
Printings
Rulings
If an effect creates multiple copies of an instant or sorcery spell, magecraft abilities trigger once for each copy created by the effect.
(wotc • 2021-04-16)
The Blood Avatar will be awakened even if no player has creatures to sacrifice when it resolves.
(wotc • 2021-04-16)
Awaken the Blood Avatar’s first ability can’t reduce its cost below {B}{R}. However, you can sacrifice any number of creatures, even if they won’t reduce its cost any further.
(wotc • 2021-04-16)
Each magecraft ability has a different effect, although they all have the same trigger condition, whenever you cast or copy an instant or sorcery spell.
(wotc • 2021-04-16)
For example, if you control Archmage Emeritus and cast an instant or sorcery spell, Archmage Emeritus’s magecraft ability will trigger and you will draw a card.
(wotc • 2021-04-16)
Some effects instruct you to copy an instant or sorcery card in a zone other than the stack. These copies do not cause magecraft abilities to trigger. However, most effects that do this also allow you to cast the copy, and casting the copy will cause magecraft abilities to trigger.
(wotc • 2021-04-16)
If an effect creates a copy of an instant or sorcery spell, this will also cause the magecraft ability to trigger.
(wotc • 2021-04-16)
As Awaken the Blood Avatar resolves, first the next opponent in turn order (or, if it’s an opponent’s turn, the opponent whose turn it is) chooses a creature they control, then each other opponent in turn order does the same knowing the choices made before them. Then all the chosen creatures are sacrificed at the same time.
(wotc • 2021-04-16)
Returning a nonlegendary creature card is not optional. If there is at least one in your graveyard, you must target it with the magecraft ability.
(wotc • 2021-04-16)
Include any additional costs to cast Awaken the Blood Avatar before applying its own cost reduction. For example, if Extus is your commander, and an additional cost of {6} applies from the “commander tax,” you may cast Awaken the Blood Avatar by sacrificing four creatures and paying {4}{B}{R}.
(wotc • 2021-04-16)