Sentinel does not have summoning sickness.
An opponent controls a creature.

Activate Gauntlets of Chaos by paying and sacrificing it, exchanging control of Altanak and target creature an opponent controls.
Declare Sentinel as an attacker, forcing Altanak to block it due to Lure.
Holding priority, activate Sentinel an arbitrarily large number of times by paying , targeting Altanak.
Altanak triggers that many times, causing an opponent to draw that many cards and lose the game due to drawing from an empty library.

Sentinel does not have summoning sickness.

Activate Coveted Falcon by paying , turning it face up.
Coveted Falcon triggers, causing an opponent to gain control of Altanak and causing you to draw a card.
Declare Sentinel as an attacker, forcing Altanak to block it due to Lure.
Holding priority, activate Sentinel an arbitrarily large number of times by paying , targeting Altanak.
Altanak triggers that many times, causing an opponent to draw that many cards and lose the game due to drawing from an empty library.

Sentinel does not have summoning sickness.

Activate Stiltzkin by paying and tapping it, giving control of Altanak to an opponent.
Declare Sentinel as an attacker, forcing Altanak to block it due to Lure.
Holding priority, activate Sentinel an arbitrarily large number of times by paying , targeting Altanak.
Altanak triggers that many times, causing an opponent to draw that many cards and lose the game due to drawing from an empty library.

Sentinel does not have summoning sickness.

Cast Wrong Turn by paying , giving control of Altanak to an opponent.
Declare Sentinel as an attacker, forcing Altanak to block it due to Lure.
Holding priority, activate Sentinel an arbitrarily large number of times by paying , targeting Altanak.
Altanak triggers that many times, causing an opponent to draw that many cards and lose the game due to drawing from an empty library.

An opponent controls a creature.
Sentinel does not have summoning sickness.

Cast Switcheroo by paying , exchanging control of Altanak and another creature with an opponent.
Declare Sentinel as an attacker, forcing Altanak to block it due to Lure.
Holding priority, activate Sentinel an arbitrarily large number of times by paying , targeting Altanak.
Altanak triggers that many times, causing an opponent to draw that many cards and lose the game due to drawing from an empty library.

Sentinel does not have summoning sickness.
Your deck size is at least 7.

Cast Fateful Handoff by paying , causing you to draw seven cards and give control of Altanak to an opponent.
Declare Sentinel as an attacker, forcing Altanak to block it due to Lure.
Holding priority, activate Sentinel an arbitrarily large number of times by paying , targeting Altanak.
Altanak triggers that many times, causing an opponent to draw that many cards and lose the game due to drawing from an empty library.

Sentinel does not have summoning sickness.

Cast Harmless Offering by paying , giving control of Altanak to an opponent.
Declare Sentinel as an attacker, forcing Altanak to block it due to Lure.
Holding priority, activate Sentinel an arbitrarily large number of times by paying , targeting Altanak.
Altanak triggers that many times, causing an opponent to draw that many cards and lose the game due to drawing from an empty library.

Sentinel does not have summoning sickness.

Cast Donate by paying , giving control of Altanak to an opponent.
Declare Sentinel as an attacker, forcing Altanak to block it due to Lure.
Holding priority, activate Sentinel an arbitrarily large number of times by paying , targeting Altanak.
Altanak triggers that many times, causing an opponent to draw that many cards and lose the game due to drawing from an empty library.

Bazaar Trader and Sentinel do not have summoning sickness.

Activate Bazaar Trader by tapping it, giving control of Altanak to an opponent.
Declare Sentinel as an attacker, forcing Altanak to block it due to Lure.
Holding priority, activate Sentinel an arbitrarily large number of times by paying , targeting Altanak.
Altanak triggers that many times, causing an opponent to draw that many cards and lose the game due to drawing from an empty library.

Blim does not have summoning sickness and cannot be blocked by an opponent.
Sentinel does not have summoning sickness.

Deal combat damage to an opponent using Blim.
Blim triggers, giving control of Altanak to an opponent.
Declare Sentinel as an attacker, forcing Altanak to block it due to Lure.
Holding priority, activate Sentinel an arbitrarily large number of times by paying , targeting Altanak.
Altanak triggers that many times, causing an opponent to draw that many cards and lose the game due to drawing from an empty library.

Sentinel does not have summoning sickness.

Activate Zedruu the Greathearted by paying , giving control of Altanak to an opponent.
Declare Sentinel as an attacker, forcing Altanak to block it due to Lure.
Holding priority, activate Sentinel an arbitrarily large number of times by paying , targeting Altanak.
Altanak triggers that many times, causing an opponent to draw that many cards and lose the game due to drawing from an empty library.