Make the monster immune to the attack type.
Also setting "lifedrain" as the attack type prevents other monsters from getting hurt by it. If it's immune of course.
Red
<attack name="water monster" interval="3000" chance="50" length="1" spread="1" min="-240" max="-360">
<attribute key="areaEffect" value="fire"/>
</attack>
</attacks>
<defenses armor="1" defense="2"/>
<immunities>
<immunity physical="0"/>
<immunity energy="0"/>
<immunity fire="100"/>
<immunity poison="0"/>
<immunity lifedrain="0"/>
<immunity paralyze="0"/>
<immunity outfit="0"/>
<immunity drunk="0"/>
<immunity invisible="0"/>
</immunities>
/m demon
/s demon
......i don't understand.....
<immunities>
<immunity lifedrain="1"/>
<immunity paralyze="1"/>
<immunity invisible="1"/>
<immunity fire="1"/>
</immunities>
<elements>
<element physicalPercent="25"/>
<element earthPercent="40"/>
<element energyPercent="50"/>
<element deathPercent="20"/>
<element icePercent="-12"/>
<element holyPercent="-12"/>
</elements>