How to use

isLifeTotalCanChange

method

in

mage.players.Player

public static List<Permanent> canKillOpponent(Game game, List<Permanent> attackersList, List<Permanent> blockersList,
                       Player defender) {
  List<Permanent> blockableAttackers = new ArrayList<>(blockersList);
  List<Permanent> unblockableAttackers = new ArrayList<>();
  for (Permanent attacker : attackersList) {
    if (!canBeBlocked(game, attacker, blockersList)) {
      unblockableAttackers.add(attacker);
      blockableAttackers.remove(attacker);
    }
  }
  sortByPower(blockableAttackers, true);
  // imagine that most powerful will be blocked as 1-vs-1
  List<Permanent> attackersThatWontBeBlocked = new ArrayList<>(blockableAttackers);
  for (int i = 0; (i < blockersList.size() && i < blockableAttackers.size()); i++) {
    attackersThatWontBeBlocked.remove(blockableAttackers.get(i));
  }
  attackersThatWontBeBlocked.addAll(unblockableAttackers);
  // now count if it is possible to win the game by this attack using unblockable attackers and
  // those attackers that won't be blocked for sure (as player will block other creatures)
  if (sumDamage(attackersThatWontBeBlocked, defender) >= defender.getLife() && defender.isLifeTotalCanChange()
      && defender.canLose(game) && defender.getLife() > 0) {
    blockableAttackers.addAll(unblockableAttackers);
    return blockableAttackers;
  }
  if (sumPoisonDamage(attackersThatWontBeBlocked, defender) >= 10 - defender.getCounters().getCount(CounterType.POISON)) {
    blockableAttackers.addAll(unblockableAttackers);
    return blockableAttackers;
  }
  return emptyList;
}

if (!player1.isLifeTotalCanChange() || !player2.isLifeTotalCanChange()) {
  return false;

@Override
public boolean apply(Game game, Ability source) {
  Player controller = game.getPlayer(source.getControllerId());
  Player player = game.getPlayer(source.getFirstTarget());
  if (controller != null && player != null) {
    int lifeController = controller.getLife();
    int lifePlayer = player.getLife();
    if (lifeController == lifePlayer) {
      return false;
    }
    if (!controller.isLifeTotalCanChange() || !player.isLifeTotalCanChange()) {
      return false;
    }
    if (lifeController < lifePlayer && (!controller.isCanGainLife() || !player.isCanLoseLife())) {
      return false;
    }
    if (lifeController > lifePlayer && (!controller.isCanLoseLife() || !player.isCanGainLife())) {
      return false;
    }
    controller.setLife(lifePlayer, game, source);
    player.setLife(lifeController, game, source);
    return true;
  }
  return false;
}

if (!player1.isLifeTotalCanChange() || !player2.isLifeTotalCanChange()) {
  return false;

@Override
public boolean apply(Game game, Ability source) {
  Player player = game.getPlayer(source.getControllerId());
  if (player != null && player.isLifeTotalCanChange()) {
    Permanent perm = game.getPermanent(source.getSourceId());
    if (perm != null) {
      int amount = perm.getPower().getValue();
      int life = player.getLife();
      if (life == amount) {
        return false;
      }
      if (life < amount && !player.isCanGainLife()) {
        return false;
      }
      if (life > amount && !player.isCanLoseLife()) {
        return false;
      }
      player.setLife(amount, game, source);
      game.addEffect(new SetPowerToughnessSourceEffect(life, Integer.MIN_VALUE, Duration.Custom, SubLayer.SetPT_7b), source);
      return true;
    }
  }
  return false;
}

@Override
public boolean apply(Game game, Ability source) {
  Player player = game.getPlayer(source.getControllerId());
  if (player != null && player.isLifeTotalCanChange()) {
    Permanent perm = game.getPermanent(source.getSourceId());
    if (perm != null) {
      int amount = perm.getToughness().getValue();
      int life = player.getLife();
      if (life == amount) {
        return false;
      }
      if (life < amount && !player.isCanGainLife()) {
        return false;
      }
      if (life > amount && !player.isCanLoseLife()) {
        return false;
      }
      player.setLife(amount, game, source);
      game.addEffect(new SetPowerToughnessSourceEffect(Integer.MIN_VALUE, life, Duration.Custom, SubLayer.SetPT_7b), source);
      return true;
    }
  }
  return false;
}

@Override
public boolean apply(Game game, Ability source) {
  Player opponent = game.getPlayer(source.getFirstTarget());
  if (opponent != null && opponent.isLifeTotalCanChange()) {
    Permanent perm = game.getPermanent(source.getSourceId());
    if (perm != null) {
      int amount = perm.getToughness().getValue();
      int life = opponent.getLife();
      if (life == amount) {
        return false;
      }
      if (life < amount && !opponent.isCanGainLife()) {
        return false;
      }
      if (life > amount && !opponent.isCanLoseLife()) {
        return false;
      }
      opponent.setLife(amount, game, source);
      perm.getToughness().modifyBaseValue(life);
      // game.addEffect(new SetPowerToughnessSourceEffect(Integer.MIN_VALUE, life, Duration.Custom, SubLayer.SetPT_7b), source);
      return true;
    }
  }
  return false;
}