This card works well with cards like Horn of the Phantom Beast, Ayers Rock Sunrise, and other cards that change the ATK of monsters on the field in your favor, while also providing a recycle or deck thinning effect.
Combo this card's effect with "Urgent Tuning". Use the effect of "Flamvell Firedog" to Special Summon a Tuner monster such as "Flamvell Magician", and then activate "Urgent Tuning" to Synchro Summon for a Level 8 monster and attack with it to deal large amounts of damage to your opponent.
This card is great support for a "Hazy Flame" deck, since it can summon a couple of that deck's key monsters. This is especially helpful if you do not yet have a "Hazy" spell/trap card out yet to aid in Normal summoning Hazys. (You will still prob need Hazy Pillar for it's 2nd effect.) Also allows a hazy flame deck to thin out even faster (than with just "Hazy Flame Cerbereus" and Hazy Flame Peryton alone) for strategic purposes.
Normal summon Cerbereus with its own effect to reduce its ATK. Then use Creature Swap to hand it to your opponent. Attack and destroy it with Firedog to deal 900 damage to your opponent's life points, trigger Firedog's search/summon effect, and also trigger Cerbereus's search effect, AND you still get a monster from your opponent.
Keep in mind that monsters special summoned during your battle phase by this card's effect can attack during that battle phase.