Gwenom, Remorseless

Attack triggers that hand you your library's crest are common enough, but the twist here is the payment schedule: cast a spell revealed this way and you pay life equal to its mana value instead of its actual cost. That inversion turns the lifelink into a self-sustaining engine rather than a footnote. The 4/4 body with deathtouch and lifelink is already a favorable attacker on its own, trading up in combat while padding the life you are spending, and the peek opens the moment it swings, not after it connects. Declare the attack and you can immediately start converting gained life into spells, mana cost be damned. The design is deliberately reckless in the way the name suggests: cheap spells cost almost nothing in life, but the ability makes no distinction for a bomb sitting up top, so a five-drop and a seven-drop both cash out at their mana value in life whether or not you can afford it. The window runs from the attack step through end of your turn, and the "any time" clause lets you keep peeking and playing across your own second main phase, not just at the trigger's resolution. It rewards a deck that keeps its life total high and its curve reachable, and it punishes greed the way life-payment cards always have. The lineage runs through the black tradition of paying life for advantage, but few tie that payment to combat and hide the price of every spell inside the same recurring attack trigger.