python3, 75 bytes

Result

AC

Duration

566ms

Code [DL]

print(''.join([chr((ord(x)+i+1-13)%26+65) for i, x in enumerate(input())]))

stdin

EOURLTZVVRJWTVNDFRBJXDVSOB

stdout

FQXVQZGDEBUIGJCTWJUDSZSQNB

stderr

strace