ネクロバインダー

• Type: Skill
• Cost: 3
• Effect: Gain 13 Block. Whenever someone dies, this card's cost is reduced by 1.

A 3-cost 13-Block Skill whose cost drops by 1 per death. In multi-enemy fights where you kill several trash mobs, or in builds where Osti is sacrificed (Bone Shard, Sacrifice), the cost keeps ticking down until Melancholy becomes a free 13 Block every turn — an extraordinary Block engine.

The death trigger likely counts player, Osti, and enemy deaths, so builds that intentionally sacrifice Osti via Bone Shard or Sacrifice naturally ramp the cost reduction. It's especially strong in long fights and fights with lots of small enemies where the kill count climbs. By late combat, it sits at cost 0-1 for 13 Block every turn — a fortress of defense.

Rating: A-tier (cost-scaling Block engine that becomes a staple in late combat)

• Early on, hold off — let kill count tick down the cost
• Bone Shard or Sacrifice intentionally kills Osti to trigger reductions
• Once cost drops to 2 or less, start playing it every turn for massive Block
• At cost 0, you gain 13 Block every turn for free — absolute defensive wall

• Bone Shard: Sacrifices Osti for AoE damage + Block. Osti's death drops Melancholy cost by 1
• Sacrifice: Osti sacrifice for max HP × 2 Block. Osti death triggers Melancholy reduction
• Reaper: Decay = Attack damage. Decay kills drop Melancholy cost every kill
• Countdown: turn-start random-enemy Decay 6. Decay deaths knock down Melancholy cost
• Final Hour: Decay-equal damage with Exude. Enemy death from Final Hour reduces Melancholy cost