Electro, Assaulting BatteryHow it works & interactions with other cards

Storing the Charge

Electro has a continuous effect that changes the standard rules of Magic: you do not lose unspent red mana as steps and phases end. While he is on the battlefield, you can accumulate red mana across multiple turns. Additionally, he provides a triggered ability that adds one red mana every time you cast an instant or sorcery spell. Note that other colors of mana and colorless mana are still lost at the end of every step or phase as normal.

The Final Spark

When Electro leaves the battlefield, his final ability triggers. This is a special two-step process called a reflexive triggered ability. First, the 'leaves the battlefield' ability goes on the stack without a target. As it resolves, you choose a value for X and pay that much mana. If you do pay, a second ability triggers immediately, and you choose the target player at that time. This allows you to see how much mana you have available before committing to a target.

Post-Electro Management

A common mistake is thinking your red mana disappears the moment Electro leaves the battlefield. According to the official rulings, you actually have until the end of the current step or phase to spend whatever red mana you have remaining before it finally vanishes. Once the current step ends, the standard rules of mana loss resume. Also, remember that any special riders on your red mana, such as restrictions on what it can be spent on, remain attached to that mana even if it is stored for several turns.

When to Play Electro

Electro is best utilized in decks with high counts of instant and sorcery spells. Because he provides flying, he can pressure opponents in the air while you build up a massive reserve of red mana. He acts as both a mana ritual engine and a finisher, making him an ideal lead for aggressive or combo-oriented red strategies.

Interaction examples

Doubling the Output with Roaming Throne

Roaming Throne

If you have Roaming Throne on the battlefield with 'Human' or 'Villain' chosen, Electro's abilities trigger twice. When you cast an instant or sorcery, you add two red mana instead of one. Furthermore, when Electro leaves the battlefield, his reflexive ability triggers twice, allowing you to pay X twice to deal damage to two different targets (or the same target twice).

Electro's Standalone Power

With Electro on the battlefield, you cast a 1-mana red instant. Electro's ability triggers and adds one red mana to your pool. Since you don't lose red mana, you can keep that mana in your pool through your opponent's turn. If Electro is then destroyed by an opponent's spell, his 'leaves the battlefield' ability triggers. You can then spend that stored red mana to pay for X, dealing damage directly to your opponent.

Sequential Triggers with Solemn Simulacrum

Solemn Simulacrum

If Electro and Solemn Simulacrum are both destroyed by a board wipe, both of their 'leaves the battlefield' or 'dies' abilities trigger. You can choose the order they go on the stack. You could resolve the Solemn Simulacrum trigger first to draw a card, then resolve Electro's ability, using your stored red mana to pay X and damage a player based on the new game state.