I believe you can set up an encounter up in a lair.
Try adding this into the encounter of the goodiehut:
<Encounter>
<Liklihood>100</Liklihood>
<BattleIdentifier>SandGolem</BattleIdentifier>
<TacticalMap>T_Ruins_Barren_01</TacticalMap>
<WillRespawn>0</WillRespawn>
<WanderingRadius>0</WanderingRadius>
<UnitInstance>
<UnitType>SandGolem</UnitType>
<Level>4</Level>
</UnitInstance>
</Encounter>