Fate's judgment and unerring strike against UD sphinxes and daemons is very painful. You can put a 1000p greater daemon down with those 2 spells.
200p artillery can shoot a 500-900p monster down before it does something. Why can a 400+ point mage reliably kill 100p per turn for maybe 6 turns. Assuming you won't get into combat or get killed and such, so maybe 3-4 turns is more realistic.
Do you take into account all the points and effort artillery need to keep it alive?
Or do you take into account that artillery is heavily limited by terrain, since it can't move quickly enough?
And do you take into account the cost of engineer, who makes artillery piece more or less reliable?