The description when building a guardian statue led me to believe that it could cast whatever spells my sovereign could.  When my city was attacked, however, the spells tab during the statue's turn was greyed out.

I looked for a debug file in the place stated in the sticky, but there wasn't one.

I'm playing through steam, custom race: lucky, scrying pools, bronze shields, one handed spears, tile fortification.  Sovereign started with death and water magic, sacrificed heroes for the three other schools available.  I rescued one champion who had some low level life spells, but I wouldn't expect those on the statue.  Huge map, 5 opponents, insane creeps, challenging factions.