Board Thread:Game Discussion/@comment-5573466-20130505204212/@comment-5573466-20130507213929

Well, the current upgrading system is pretty straightforward.

T3 gives more EXP than T2, and cards with higher stats gives more EXP.

Btw, it takes around 200x T2 to upgrade a T4 to lvl 65 (without the EXP boost during events) and 200,000 credits.