It is absolutely important to note that this card only works under the assumption that your opponent will attack. Without that, the card does nothing but stall a weary opponent who would sooner destroy the card outright. Knowing this, a proper strategy would be to force the attack using cards like "Staunch Defender", "All-Out Attacks", "Battle Mania" and "Savage Colosseum".
If you plan to use this card along with "Scrap-Iron Scarecrow" or other similar trap/spell cards, use "Blast Asmodian" as well. you will inflict 500 damage from an attack being declared against you, then when you play a trap/spell card (which will resolve at the same time starting a chain link of 2), "Blast Asmodian" will inflict a further 500 damage. Furthermore, any chain links of 2 or higher that involve spell/trap cards will cary on inflicting 500 damage making this a powerful burn combo.
If you special summon this card, you can summon two more with "Inferno Reckless Summon" and make your opponent take 1500 damage each attack.
Use this card if you want to protect other cards, because your opponent will probably want to destroy this card first. If not, then he/she will have to sacrifice LP. This card is better when you face a deck which destroys cards by attacking. Cards like "Smashing Ground", "Caius the Shadow Monarch", "Master Hyperion" will make this card useless, because they will remove it before you can take advantage of its effect.