If used the right way, this card can be very effective in a "Final Countdown" Deck. This is because the Deck already has so much Stall elements in it that adding "Ancient Forest" would still slow down your opponent's offense as their attacking monsters get destroyed.
Either "Zero Gardna" or "Waboku" can also be used to further slow down your opponent's offense, because not only will their attacking monster be destroyed, any damage will also not be taken from the attack.
This card could also work well in a dedicated "T.G." Deck; since most of the "T.G." monsters search out replacements when destroyed, this will stop your opponent's attacks, while allowing your monsters to attack without losing Card Advantage. Keep in mind, though, that this will leave your Life Points vulnerable if all your monsters attacked.
This card has great synergy with "Dimensional Prison". If your opponent decides to attack, chances are it is a monster whose effect activates in the Graveyard, which "Dimensional Prison" will thwart.
This card can be used to change all your opponent's monsters to attack mode. Then attack and before the end of the Battle Phase, active "Scrubbed Raid" to send this card to the Graveyard and prevent the destruction of your monsters.
This card can be used to change all your opponent's monsters to attack mode and attack with "Mist Valley Falcon" to return this card to you hand and use during each turn.
This card combos really well with "Alector, Sovereign of Birds". When the attack occurs, have your "Alector" negate the the effect of the Field Spell, and attack at will. When the end of your turn, the Field Spell will regain its effect, making sort of a spear and shield type offensive strategy.
Use the effect of "Dewloren, Tiger King of the Ice Barrier" to return this card to your hand to avoid destruction effect, and then activate it again during Main Phase 2, so it can only destroy your opponent's monsters.
A good way to raise a fair bit of burn damage is to have a "Spear Cretin" in the Graveyard and another one on the field in face-down defense. With this card on the field wait for the opponent to Special Summon then activate "All-Out Attacks" and "Coffin Seller".
This combo seems effective against Swarm strategies. Have this card, plus "Astral Barrier", "Spirit Barrier" and "Coffin Seller". If the opponent attempts to attack; all their attacks will fail, their monsters will be destroyed and they'll take 300 damage for each one destroyed this way.
Use this card to switch monsters in attack mode, then Special Summon "Ancient Fairy Dragon" and use its effect to destroy this card to then attack.
When your opponent swarms the field, use "Demise of the Land" to activate this card from your Deck. If they decide to attack, they'll be left defenseless next turn, or it will deter the opponent from attacking with their strongest monster.