Notes & Combos
If you're going first then during opponent's turn, Cynet Backdoor the Firewall/Encode/Decode to search Mathmech Addition before next turn. In next turn, Mathmech Addition effect to Cynet Backdoored monster by raising it with 1000 atk (make sure it's over than 3200 atk) then link summon Flame Administrator other than cynet backdoored monster for it to reach 4000+ atk. Easy direct attack win while avoiding opponent monsters, make sure to aware of opponent's magic cylinder.
Replays
Example: https://duellinks.konami.net/att/02f95a65a54abd38ab00eb69a774f5c7ca5682713e
Firewall Dragon double return monsters effect (just to show it without a double cynet backdoored linkslayer and firewall could end the game):https://duellinks.konami.net/att/07b383801d776c9f4091bf9fcb1641b14d636d64d0