AGE system freeform magic system, Fantasy AGE RPG

I've been toying with the idea of freeform magic for Green Ronin's Fantasy AGE system. Using both Ubiquity and D6 system as inspiration I created some basic guidelines. I'll refine them as I go.

To cast a magical effect the player describes the effect they wish to cast. The player calculates any bonuses or penalties based on Range, area effect, familiarity, and time. 

The GM looks over the spell effects and decided the appropriate base cost. Take the base difficulty and add bonuses and penalties plus ten. This final number is the cast difficulty.

Casting difficulty:

TN of spell effects is 10+ spell effect, then add bonuses or penalties for Range, Area of effect, familiarity, and time. Casting rolls are made on Intelligence with focuses being the four spell type catagories.

Range:
Touch -1
Close   0 (within 10 yards)
Medium +1 (within 30 yards)
Long +2 (within 50 yards)
Extreme +3 (within 100 yards)

Area of Effect:
Single target 0
Circle, small 6yard, +1
Circle, large 10yard, +2
Cone or beam +1 

Familiarity:
Held, touched, true name -1
Seen up close, conversed 0
Seen from a distance,  +1
Can't see but know it's presence, +2

Time:
End of turn/Instant. 0
End of round. +1
End of end of scene/combat. +2
End in an hour. +3

Spell effects:

Control (push/pull)
1 really small object, under 5 pound
2 Small object, up to 20 pounds
3 medium object, up to 100 pounds
4 large object, up to 200 pounds

5 extreme object, up to 600 pounds

Alter/Enchant
1 change appearance, superficial.
2 limited physical change, property. +1
3 strong but uncomplicated, nature. +2
4 Significant and invasive, +3
5 powerful and complicated. +4

Create/Conjure
1 simple raw material
2 small simple items
3 summon mindless,tool, weapon,
4 summon larger, complex, attack animal,
5 summon intelligent attack, large.

Damage/Heal
Chosen 1-6 for difficulty.
Damaging or Healing effect equals 1d6 plus a bonus equal to the difficulty.
Apply an element or source for damage add +2 difficulty. Damage is penetrating x 2 difficulty.

For example the mage character wants to knock down a bolder from above a goblin camp. The bolder is about 200 lbs and it's 30 feel away. Looking at Control the GM sets the difficulty to 15. (4 for weight, +1 for range, +10). The bolder comes rolling down causing the goblin guards to go investigate.

My original idea was for a system without magic points. But if using magic point cost to cast would be equal to final spell effect. Final cost equal to spell difficulty -10. Using the example above the Mana cost would have been 5 MP.

Another option is drain, rather than having magic points characters could have a backlash or drain for failed rolls. The idea here is that Characters can play it safe with easy difficulties, or push their luck and risk more. My first idea for this is on a failed roll the character takes damage to their health equal to the difference in their roll. If the spell effect TN is 15 and the player rolls a 10 he would take 5 damage.

Another option is that for every 5 the player rolls below the TN the character takes 1d6 penetrating damage.