Once a creature is "blocked", it stays blocked unless something makes it not a blocker anymore. Giving your dude flying via unmorph isn't good enough, as it is already "blocked".
During the Declare Blockers (and Declare Attackers) step, no abilities are allowed, not even unmporhing. After Nessie is declared a blocker blocking Vamp, then Vamp is blocked.
Spells and activated abilities CAN be played during the declare attackers and declare blockers steps. They cannot be played during the time when attackers and blockers are being declared (which is part of what happens during those 2 steps, but not all).
Also, while a creature, once blocked, remains blocked, that doesn't really tell the whole tale in this case. All blocks must be legal when blockers are declared. That's the only time such legality is checked. If Creature A is blocking Creature X, and after that something changes so that it would not be legal to declare X as a blocker for A, that won't change anything, it just prevents X from being declared as a blocker for A, it won't undo any blocking assignments already made.
So if I can try and understand this;
What I was doing was legal
Declare face-down Soul Collector as an attacker
Opponet declares Nessian as the blocker for Soul Collector
I pay
to turn face-down Soul Collector face-up
I kill Nessian with Soul Collector and gain control of Nessian via Soul Collector's ability
Sorry for the misuse of the word 'morphed' - I swear the lingo of this game is more difficult to remember then the actual rules!'
If you could clarify for me Clariax I would appreciate it.
