Entrench

Entrench is a 2-Energy Ironclad skill (1 upgraded) that doubles your current Block. Its power scales directly with how much Block you already have: with 20 Block, Entrench gives you 20 more for 2 Energy; with 40 Block, it gives you 40 more. This makes it an exponential scaling card in Block-heavy builds, particularly Barricade builds where Block carries over between turns and can accumulate to massive values.

Entrench is weak early in a fight before you've built Block, but in the mid-to-late turns of a long encounter it can generate overwhelming protection. Upgrade priority is high — reducing from 2 to 1 Energy lets you use it alongside other Block cards in the same turn. A cornerstone card in any Barricade or Block-doubling archetype.