リージェント

• Type: Skill
• Cost: 0 (2 stars)
• Effect: Gain 9 Block. Return this card to your hand.

Upgraded

• Cost: 0 (2 stars)
• Effect: Gain 12 Block. Return this card to your hand.

A fantastic repeatable defense card: 9–12 Block for 0 energy at the cost of 2 stars, and it returns to your hand after use. As long as stars keep flowing, you can fire it as many times as you want, stacking huge amounts of Block in a single turn.

Its synergy with Star Child (gain Block whenever you spend stars) is brutal — Particle Barrier x2 is 9+9=18 Block plus Star Child's 4–6 star-spend bonus, so 22–24 Block in a single turn at 0 energy. As long as star income is steady, this is one of the strongest defensive cards in the game.

• On turns with spare stars, fire it repeatedly — pile on Block aggressively when stars are abundant
• With Star Child in play, every use adds bonus Block, so spam it
• It doesn't thin the deck since it returns to hand, but it serves as a reliable ongoing defense tool

• Star Child: 2–3 Block per star spent. Every Particle Barrier use layers on extra Block
• Genesis: supplies 2–3 stars at the start of each turn, making Particle Barrier playable every turn
• Black Hole: AoE damage every time you spend stars. Spamming Particle Barrier means offense and defense in one motion
• Reflect: converts stored Block into damage later. Block piled up by Particle Barrier can be flipped into attack

• Regent Defense-Reflect Build (key card) (A-tier)
• Regent Debuff Control Build (B-tier)