Harpie's Pet Phantasmal Dragon — Ruling

Regola generale

Regarding the『This card's effects can only be applied/resolved while it has material.』text:
This is not treated as an effect.

Regarding the『Your opponent cannot target any "Harpie" monsters with effects or for attacks.』effect:
This effect is a Continuous Effect, which applies in the Monster Zone.
『Your opponent cannot target any "Harpie" monsters for attacks.』is an effect that is applied to your opponent's monsters. (Any of your opponent's monsters that are unaffected by monster effects can target your "Harpie" monsters for attacks.)
『Your opponent cannot target any "Harpie" monsters with effects.』is an effect that is applied to your opponent. (Even if any of your opponent's cards are unaffected by monster effects, your opponent still cannot target your "Harpie" monsters with those cards' effects.)
Even if this effect is applying, your opponent can still target "Harpie" monsters in the Graveyard, or "Harpie" monsters that are banished.

Regarding the『Detach 1 material from this card.』effect:
This effect is a Trigger Effect, which must be activated in the Monster Zone.
If this card has Xyz Materials, this effect will always activate during the End Phase.