sand_wyrm_corrosion.xml

<statusEffects>
  <statusEffect>
    <turns>12</turns>
    <name>Corrosion</name>
    <key>sand_wyrm_corrosion</key>
    <type>Debuff</type>
    <icon>corrosive_sand</icon>
    <skipFirstTurn>true</skipFirstTurn>
    <description>
      Corrosive sand permeates your armor, eroding it temporarily.
    </description>
    <modifiers>
      <modifiers>
        <type>PhysicalResist</type>
        <amount>-0.25</amount>
      </modifiers>
    </modifiers>
  </statusEffect>
</statusEffects>