Edison format ruling
Raviel, Lord of Phantasms

Card effect (current official text)Cannot be Normal Summoned/Set. Must be Special Summoned (from your hand) by Tributing 3 Fiend-Type monsters, and cannot be Special Summoned by other ways. If your opponent Normal Summons a monster(s): Special Summon 1 "Phantasm Token" (Fiend-Type/DARK/Level 1/ATK 1000/DEF 1000) for each monster Summoned, but it cannot declare an attack. Once per turn: You can Tribute 1 monster; this card gains ATK equal to the original ATK of the Tributed monster until the end of this turn.
Rulings
- You can Tribute face-down Fiends to Special Summon "Raviel, Lord of Phantasms".
- Tributing 1 monster is a cost to activate this card’s Ignition Effect. You cannot Tribute this card for its own effect.
- If your opponent Normal Summons a monster in a chain using "Ultimate Offering", resolve all effects in that chain, then activate the effect of "Raviel, Lord of Phantasms" to start a new chain. If the Normal Summon for "Ultimate Offering" was Chain Link 2 or higher, you still activate the effect of "Raviel". It does not miss the timing.
- If all of your Monster Card Zones are full, this card’s effect will activate, but if there are no available spaces when the effect resolves, the effect is not applied.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Edison forum — sourced change requests get reviewed.