Just ride the MTR Line 4, to Seoul Grand Park Station, after exit, go to the ground, and walk for about 800M, and then you will arrive it.
The way from the MTR exit to Seoul land is covered with snow. Kids love it so much.
There is discount for tourist, adult and child all charge only KRW$13000. I didn't show any coupon, and the cashier just give me the discount.
But i feel that it's no so popular coz it's really cold on the date i went, (it's -11 degree). So please wear enough jacket, scarf, hat and better with face mask.