I'm relatively new to modding this game, and I wasn't sure if I was pulling a stat the other day, so I used the formatted description of the spell to check it.  Example:

<SpellDef InternalName="GinsuKnife">
        <DisplayName>Throwing Knives</DisplayName>
        <Description>Throw knives at a nearby enemy.</Description>
        <FormattedDescription>The pulled stat value is %d</FormattedDescription>
        ...
        <GameModifier>
            <ModType>Unit</ModType>
            <Attribute>DefendableDamage</Attribute>
        <IsForFormattedDescription>1</IsForFormattedDescription>
            <Calculate InternalName="Calc" ValueOwner="CastingUnit">
                <Expression><![CDATA[[Unit_GetLevel]]]></Expression>
            </Calculate>
            ...
            <Calculate InternalName="ValueForFormattedDescription"  ValueOwner="CastingUnit">
                <Expression><![CDATA[[Calc]]]></Expression>
            </Calculate>
        </GameModifier>
        ...
    </SpellDef>

In the code above, I'm attempting to pull the unit's level.  I apply the attempted pull to "Calc" then designate [Calc] as the value for the formatted description.

In game, I can check to see if I'm pulling the stat properly by mousing over my special ability (see screenshot below).

OK, I edited this like 10 times to get the colors right, and it still sucks... I hate HTML editors