How to use

declareBlocker

method

in

mage.players.Player

if (blockers != null) {
  for (Permanent blocker : blockers) {
    player.declareBlocker(player.getId(), blocker.getId(), attackerId, game);
    blocked = true;

creatureMustBlockAttackers.put(possibleBlocker.getId(), forcingAttackers);
defender.declareBlocker(defender.getId(), possibleBlocker.getId(), attackingCreatureId, game, false);

      && attackersToBlock.contains(attackingCreatureId)) {
    defender.declareBlocker(defender.getId(), creature.getId(), attackingCreatureId, game);
  if (creature.canBlock(attackingCreatureId, game)
      && !findGroup(attackingCreatureId).getBlockers().contains(creature.getId())) {
    defender.declareBlocker(defender.getId(), creature.getId(), attackingCreatureId, game);
    break;
  removeBlocker(possibleBlockerId, game);
defender.declareBlocker(defender.getId(), possibleBlockerId, toBeBlockedCreatureId, game);

UUID attackerId = group.getAttackers().get(0);
for (UUID blockerId: group.getBlockers()) {
  sim.getPlayer(defenderId).declareBlocker(defenderId, blockerId, attackerId, sim);

public static SurviveInfo willItSurvive(Game game, UUID attackingPlayerId, UUID defendingPlayerId, Permanent attacker, Permanent blocker) {
  Game sim = game.copy();
  Combat combat = sim.getCombat();
  combat.setAttacker(attackingPlayerId);
  combat.setDefenders(sim);
  if (blocker == null || attacker == null || sim.getPlayer(defendingPlayerId) == null) {
    return null;
  }
  sim.getPlayer(defendingPlayerId).declareBlocker(defendingPlayerId, blocker.getId(), attacker.getId(), sim);
  sim.fireEvent(GameEvent.getEvent(GameEvent.EventType.DECLARED_BLOCKERS, defendingPlayerId, defendingPlayerId));
  sim.checkStateAndTriggered();
  while (!sim.getStack().isEmpty()) {
    sim.getStack().resolve(sim);
    sim.applyEffects();
  }
  sim.fireEvent(GameEvent.getEvent(GameEvent.EventType.DECLARE_BLOCKERS_STEP_POST, sim.getActivePlayerId(), sim.getActivePlayerId()));
  simulateStep(sim, new FirstCombatDamageStep());
  simulateStep(sim, new CombatDamageStep());
  simulateStep(sim, new EndOfCombatStep());
  // The following commented out call produces random freezes.
  //sim.checkStateAndTriggered();
  while (!sim.getStack().isEmpty()) {
    sim.getStack().resolve(sim);
    sim.applyEffects();
  }
  return new SurviveInfo(!sim.getBattlefield().containsPermanent(attacker.getId()), !sim.getBattlefield().containsPermanent(blocker.getId()));
}