Morlun, Devourer of Spiders is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Lifelink Morlun enters with X +1/+1 counters on him. When Morlun enters, he deals X damage to target opponent.

Complete guide

Morlun, Devourer of Spiders is a powerful Legendary Vampire Villain that scales perfectly from the early game to the late game. This commander demands a high mana investment but rewards you by weakening your enemies while simultaneously bolstering your health and board presence. With his built-in Lifelink and enter-the-battlefield trigger, Morlun ensures that no opponent is safe from his predatory reach.

What Morlun Does

Morlun, Devourer of Spiders uses a variable mana cost represented by {X}. As he enters the battlefield, he receives a number of +1/+1 counters equal to the value you chose for X, which determines his starting power and toughness. Additionally, he features a triggered ability that deals direct damage to a chosen opponent based on that same X value, paired with Lifelink to keep your life total high.

Resolving the Summon

When you cast Morlun, you first choose a value for X and pay the corresponding mana. Upon resolution, Morlun enters the battlefield with the counters already on him; there is no window for opponents to kill him before he has his stats. Immediately after he enters, his damage ability goes on the stack. Because Morlun has Lifelink, the damage he deals to an opponent will cause you to gain that much life simultaneously.

Strategic Timing

Since Morlun's power depends on X, he is a fantastic mana sink for the late game. However, even casting him where X is 0 can be a valid strategic move if you simply need to trigger 'enters the battlefield' or 'dies' effects for other cards on your board. Remember that the damage ability targets an opponent, so it can be countered if the opponent gains Hexproof in response.

Common Pitfalls

A common mistake is forgetting that Lifelink applies to all damage dealt by the creature, not just combat damage. Another error is miscalculating the total mana cost; remember you must pay the two Black mana in addition to whatever value you choose for X. If Morlun is countered while on the stack, his damage ability will never trigger because he never entered the battlefield.

Interaction examples

Fueling the Devourer

Ornithopter of Paradise

You tap Ornithopter of Paradise for one mana and combine it with four other lands to cast Morlun where X equals 3. Morlun enters as a 3/3 creature. His ability triggers, dealing 3 damage to an opponent and gaining you 3 life due to Lifelink.

The Death Cycle

Blood Artist

With Blood Artist on the battlefield, you cast Morlun where X is 0. Morlun enters as a 0/0 and immediately dies as a state-based action. While Morlun deals 0 damage, his death triggers Blood Artist, causing an opponent to lose 1 life and you to gain 1 life.

Guide written with AI from the official text and rulings. Official English text prevails.