My opponent attacks me with a Phantasmal Dragon and I return Gossamer Chains to my hand to prevent the damage. Does the dragon die from being targeted?
Yes, your opponent has to sacrifice the Dragon, since it became the target of an ability. It doesn't matter, what the spell or ability would do to its targets, just that it targets the Dragon. To see wether a spell/ability targets look for the word "target", it has to be there for all targeted spells/abilities, either in the card's text or the rules text for its abilites. Auras spells target, because the rules for the enchant ability say so.
Note, that you cannot activate the Chains before the declaration of blockers, since no unblocked creature exists before then, so no legal target.
Note, that you cannot activate the Chains before the declaration of blockers, since no unblocked creature exists before then, so no legal target.
Former Rules Advisor
"Everything's better with pirates." - Lodge
(The Gamers: Dorkness Rising)
"Any sufficiently analyzed magic is indistinguishable from science."
(Girl Genius - Fairy Tale Theater Break - Cinderella, end of volume 8)