Symmetrical template.

By the way, sorry for the off-topic, but I don't know where else to ask. Just out of curiosity, what data structure is used to store the skill tree, and what is the construction scheme? If it's just a binary tree, then to fill all the slots, you need 28 levels, which means 28 levels of the tree. That results in 2^29 - 1 = 536,870,911 vertices. There are only 28 secondary skills, which means one byte per vertex. That's gigabytes of information for each hero.