Zealot il-Vec

• WWizards of the Coast2006-09-25
  Official Ruling
  If you choose to have Zealot il-Vec deal 1 damage to a creature and that damage is prevented or replaced, Zealot il-Vec’s combat damage will still be prevented.
• WWizards of the Coast2006-09-25
  Official Ruling
  When Zealot il-Vec attacks and isn’t blocked, you must choose a target for its ability even if you don’t use it.
• WWizards of the Coast2013-04-15
  Official Ruling
  An ability that triggers when something “attacks and isn’t blocked” triggers in the declare blockers step after blockers are declared if (1) that creature is attacking and (2) no creatures are declared to block it. It will trigger even if that creature was put onto the battlefield attacking rather than having been declared as an attacker in the declare attackers step.
• WWizards of the Coast2021-03-19
  Official Ruling
  If an attacking creature has multiple evasion abilities, such as shadow and flying, a creature can block it only if that creature satisfies all of the appropriate evasion abilities.
• WWizards of the Coast2021-03-19
  Official Ruling
  Multiple instances of shadow on the same creature are redundant.
• WWizards of the Coast2021-03-19
  Official Ruling
  Once a creature has been blocked, that creature remains blocked and will deal and be dealt combat damage even if it gains or loses shadow or if the blocking creature gains or loses shadow.

Rulings via Scryfall