While I'm actually against showing players the "internal stuff" like the magic or fire resistance of a unit, it's unreasonable
to expect all players to be able to figure out how much damage a fireball may do when fired on a particular unit.
Some certainly will dig up all the values from the XML and run spreadsheets but surprisingly, some just want to play the game...

So. When aiming a spell in the tactical battle (or if there will once be strategical damage spells...) the mouseover display would
have to show what range of damage the spell could do to that particular target
with all shards / intelligence / buffs / debuffs / items / what-have-you figured in.

A simple range like:
10 - 45 damage
 +  8 damage per turn for 3 turns.

or:
Increase the strength of the unit by 10 for 5 turns.

This would solve a lot of transparency problems (and help with testing = ) once the magic system gets fleshed out.
For instance, I could imagine a MOM-style darkness spell that would benefit all things evil.
While this spell is in effect, the player can see an obvious increase of the damage range of his evil spells so even a
completely non-technical player could get a gut feel of complex systems with resist buffs and debuffs and use them
without having to know the actual math behind them.

Learning more about the game should give a bonus for the long term strategy (altering the conditions to make your
spells more effective) and not be required for menial tasks like casting a single damage spell.
That only hurts the illusion of the player being the mighty channeler who does such things blindfolded.