
Electro, Assaulting Battery | Legendary Creature | Human Villain | Flying
You don't lose unspent red mana as steps and phases end.
Whenever you cast an instant or sorcery spell, add {R}.
When Electro leaves the battlefield, you may pay {X}. When you do, he deals X damage to target player. | Dmitry Burmak

J. Jonah Jameson | Legendary Creature | Human Citizen | When J. Jonah Jameson enters, suspect up to one target creature.
Whenever a creature you control with menace attacks, create a Treasure token. | Olivier Bernard

Araña, Heart of the Spider | Legendary Creature | Spider Human Hero | Whenever you attack, put a +1/+1 counter on target attacking creature.
Whenever a modified creature you control deals combat damage to a player, exile the top card of your library. You may play that card this turn. (Equipment, Auras you control, and counters are modifications.) | Alexander Mokhov

Ultimate Green Goblin | Legendary Creature | Goblin Villain | At the beginning of your upkeep, discard a card, then create a Treasure token.
Mayhem {2}{B/R} (You may cast this card from your graveyard for {2}{B/R} if you discarded it this turn. Timing rules still apply.) | Caio Cacau

Scarlet Spider, Ben Reilly | Legendary Creature | Spider Human Hero | Web-slinging {R}{G} (You may cast this spell for {R}{G} if you also return a tapped creature you control to its owner's hand.)
Trample
Sensational Save — If Scarlet Spider was cast using web-slinging, he enters with X +1/+1 counters on him, where X is the mana value of the returned creature. | Alexandre Honoré