You don't lose unspent red mana as steps and phases end.
Whenever you cast an instant or sorcery spell, add .
When Electro leaves the battlefield, you may pay . When you do, he deals X damage to target player.
Electro is a mono-red mana engine: hold red across phases and turns, then chain instants and sorceries that each refund to build an explosive mana pool. Use that pool to fuel huge X spells, storm-style chains, or pour it into a damage outlet, and cash Electro's death trigger for a big finishing burst. You ramp on rituals and rocks early, then spend a single turn unloading your hand for lethal.
Each instant/sorcery cast refunds , making spell chains effectively cheaper and enabling storm-like turns
Persistent red mana across phases/turns means you can stockpile huge pools for X spells and instant-speed haymakers
Cheap, evasive 3-mana body that doubles as a removal-immune burn finisher via its death trigger
Mono-red gives consistent rituals, rocks, and impulse draw to feed the engine
Mono-red struggles with sustained card advantage and resilient board wipes
The engine demands a critical mass of cheap spells; a clunky draw stalls hard
Removing or countering Electro shuts off the mana refund (though the death damage offsets this)
Vulnerable to graveyard hate and Stax pieces that tax or stop spellcasting
Limited interaction with artifacts/enchantments compared to other colors
Legendary Creature — Human Villain
. When you do, he deals X damage to target player.