Vantom

Vantom is one of the Act 1a bosses encountered in the Overgrowth and is widely regarded as one of the most difficult Act 1 bosses in Slay the Spire 2. Vantom's aggressive attack pattern delivers high burst damage early in the fight, punishing decks that rely on slow setup or lack early defensive tools. Many runs end at Vantom when players underestimate the damage output.

Surviving Vantom requires front-loaded defense and damage. The Ironclad should prioritize Shrug It Off, Iron Wave, and Flame Barrier for Block, while Bash into Vulnerable lets damage cards like Pommel Strike and Twin Strike deal amplified damage. Impervious is a run-saving card against Vantom's burst turns. The Silent needs Backflip, Dodge and Roll, and Leg Sweep for emergency Block, while Bouncing Flask and Deadly Poison provide sustained damage between defensive turns. Footwork dramatically improves your ability to survive Vantom's attacks. The Defect should channel multiple Frost orbs to generate passive Block, with Dualcast on a Frost orb providing emergency defense.

The Necrobinder relies heavily on Osty to absorb Vantom's burst damage, making Summon cards essential for keeping Osty alive through the onslaught. Doom stacks from Blight Strike can set up a mid-fight execution if you reduce Vantom's HP to the threshold. The Regent should use Venerate's Block generation defensively while building Stars for post-fight Forge upgrades. Against Vantom, having at least one strong Block card is more important than raw damage. Card upgrades at Rest Sites before the boss fight can make the difference between life and death. Vantom is the primary reason many players prefer the Underdocks path in Act 1b over the Overgrowth.