by Durst » Sat May 17, 2014 3:42 pm
It's a chance. When you strengthen a card with cards that have the exact same skill name (Earth Breath II is different from Earth Breath III), you have a chance of 15% times the number of cards with the skill of increasing the target card's skill. So if you strengthened a Spiked Swordfish with six Swordfish, you would have a 90% chance of skilling up your Spiked Swordfish by one level. 90% is the maximum chance per individual strengthening. If you instead strengthened the Spiked Swordfish with two Swordfish, two other Spiked Swordfish, and two Earth Gravellers, you would have a 60% chance (15% times 4).