Costs:
Baseline = +1
Each colourless mana = +1
Each coloured mana = +2
Total mana cost of 5 or more = +1 (+2 for Green)
Benefits:
Each 1 Power or 1 Toughness = +1
Being Red or Blue creature = +1
First up is the Isolated Boy.
His costs include:
1. The card baseline. (1)2. Three colourless mana. (3*1=3)
3. One coloured mana. (1*2=2)
4. The cost so far is >= 5, but the card is not green, so there's only an added cost of one. (1)
5. Together, that equals 7.
His benefits include:
1. Power of 3.
2. Toughness of 4.
3. Not a Red or Blue creature. (0)
4. Together, that equals 7.
Isolated Boy's cost (7) equals its benefits (7), and is therefore balanced.
Next up is the Toddler's Drawing.
His costs include:
1. The card baseline. (1)2. One colourless mana. (1*1=1)
3. One coloured mana. (1*2=2)
4. The cost so far is not >= 5, so there's no added cost. (0)
5. Together, that equals 4.
His benefits include:
1. Power of 2.
2. Toughness of 2.
3. Not a Red or Blue creature. (0)
4. Together, that equals 4.
Toddler's Drawing's cost (4) equals its benefits (4), and is therefore balanced.
Finally, we have Linkolian. No he is not Link from Nintendo's "The Legend of Zelda", he just looks strikingly similar to him. Sheer coincidence, honest! =P
His costs include:
1. The card baseline. (1)2. Fifteen colourless mana. (15*1=15)
3. One coloured mana. (1*2=2)
4. The cost so far is >= 5, and the card is green, so there's an added cost of two. (2)
5. Together, that equals 20.
His benefits include:
1. Power of 10.
2. Toughness of 10.
3. It is not a Red or Blue creature. (0)
4. Together, that equals 20.
Linkolian's cost (20) equals its benefits (20), and is therefore balanced.
So that's that. Whadda ya guys think? Fancy? =]