Darksteel MonolithHow it works & interactions with other cards

Unbreakable Acceleration

The first thing to note is that Darksteel Monolith is Indestructible, meaning most removal spells like 'Destroy' effects or lethal damage won't touch it. Its primary ability allows you to cast one colorless spell from your hand each turn for {0} instead of its mana cost. This isn't limited to your own turn; you can use this ability on an opponent's turn if the spell has Flash or is an Instant.

The Resolution Process

When you choose to cast a spell using the Monolith's ability, you follow the standard casting process. First, announce the spell and move it from your hand to the stack. Then, choose the alternative cost of {0} provided by the Monolith. You still follow all timing restrictions—you cannot cast a creature without Flash during an opponent's turn just because it is free. Finally, if the spell has any mandatory additional costs, you must pay those even if the mana cost is {0}.

Alternative Costs and Constraints

A common mistake is trying to combine multiple alternative costs. If you use Darksteel Monolith to pay {0}, you cannot use other alternative costs like 'Mutate' or 'Prowl'. However, you can still pay additional costs, such as Kicker or Ward costs, and you must pay any mandatory additional costs. Also, remember that this effect only applies to spells cast from your hand; it will not work for spells cast from your graveyard, exile, or the command zone.

Strategic Timing

Because the ability resets 'once each turn,' you get the most value by casting a free spell on your turn and another free spell on an opponent's turn if you have colorless cards with Flash. It is often best to lead with your most expensive colorless spell to maximize the mana you are saving.

Interaction examples

Immediate Removal

Meteor Golem

With Darksteel Monolith on the battlefield, you can cast Meteor Golem from your hand by paying {0} instead of {7}. Once the Golem enters the battlefield, its triggered ability will trigger, allowing you to destroy a nonland permanent an opponent controls without spending a single mana.

Building an Instant Army

Myr Battlesphere

You can use the Monolith's ability to cast Myr Battlesphere for free during your main phase. The Battlesphere will enter the battlefield and create four 1/1 Myr tokens. This allows you to develop a massive board presence while keeping all your lands untapped for other spells or interaction.