Let's look first at Wave-Motion Inferno:
While you have no cards in your hand, face-up "Infernity" monsters you control gain 400 ATK and DEF. You can send this face-up card from the field to the Graveyard to send all cards from your hand to the Graveyard.
This Continuous Spell Card is pretty simple. Its first effect is continuously applied, and as you can probably tell, as soon as you have Cards in your Hand, the ATK/DEF boost stops being applied. The second effect is an Ignition-like effect, so you can only activate it during your Main Phases. Sending WMI to the Graveyard is a cost, so you cannot activate this effect while a Card like Macro Cosmos is active. If Macro Cosmos is chained, all Cards in your Hand are Removed from Play.
Next, we have Into the Void:
Activate only if you have 3 or more cards in your hand. Draw 1 card. During the End Phase of this turn, discard all the cards in your hand.
Into the Void isn't an Infernity Card per se, but some people consider it as one. Having 3 Cards in your Hand is an activation requirement, which means that Into the Void will resolve properly even if your Hand size is lower than 3 Cards when it resolves. This allows you to activate ItV if you only have 2 Cards in your Hand along it, as you would be having 3 Cards total. The effect that discards all Cards in your Hand doesn't start a chain. If you send ItV to the Graveyard via Diamond Dude's effect, you can skip the requirement of having 3 Cards in your Hand, but you must still discard your Hand during the End Phase.
Moving on, we have ZERO-MAX:
Activate only if you have no cards in your hand. Select 1 "Infernity" monster in your Graveyard. Special Summon it, and destroy all face-up monsters on the field with ATK lower than the Special Summoned monster's ATK. You cannot conduct your Battle Phase during the same turn you activate this card.
ZERO-MAX is a really peculiar Normal Spell Card. You can only activate it if you have no Cards in your Hand. However, if ZERO-MAX is in your Hand, then you do have Cards in your Hand, so you cannot activate it directly from your Hand like most Spell Cards. You must set it first. With that said, ZERO-MAX targets one Infernity monster. Once it is Special Summoned, you destroy all face-up monsters with lower ATK than that monster. The Summon and the destruction are not simultaneous, so neither player can respond to the Summon. This would cause Infernity Archfiend to miss the timing. Note that you can activate ZERO-MAX even if there are no monsters to destroy. Back to the usual restriction, if you have Cards in your Hand when ZM resolves, it will resolve without effect. And finally, if you use ZM along Diamond Dude, you can conduct your Battle Phase.
The last Spell Card is the heart and soul of the Deck, Infernity Launcher:
Once per turn, you can send 1 "Infernity" monster from your hand to the Graveyard. While you have no cards in your hand, you can send this card from the field to the Graveyard to select up to 2 "Infernity" monsters in your Graveyard and Special Summon them.
This Continuous Spell Card has two effects. The first effect is an Ignition-like effect, which helps reducing your Hand size. Launcher needs to remain face-up in order for this effect to resolve properly. The second effect is also an Ignition-like Effect, which sends Launcher to the Graveyard as a cost and targets up to 2 Infernity monsters. If one of the targets is no longer in the Graveyard, you still Special Summon the other one. If you have Cards in your Hand, as usual, Launcher will resolve without effect. Finally, if Macro Cosmos is active, you cannot pay Launcher's cost, so you cannot activate its second effect.
There are the few, but powerful Spell Cards for the Infernity theme. Stay tuned for the last article about Infernities! If you have any questions, feel free to drop me an e-mail at ness00[at]gmail[dot]com.