* Fixed that creatures that have to pay costs to block were wrongly forced to block causing UI locks.

Mage.Client/src/main/java/mage/client/game/HelperPanel.java

@@ -76,7 +76,10 @@ public class HelperPanel extends JPanel {
         setOpaque(false);
 
         JPanel container = new JPanel();
+
         container.setPreferredSize(new Dimension(100, 30));
+        container.setMinimumSize(new Dimension(20, 20));
+        container.setMaximumSize(new Dimension(2000, 100));
         container.setLayout(new GridBagLayout());
         container.setOpaque(false);
 

Mage.Server.Plugins/Mage.Player.Human/src/mage/player/human/HumanPlayer.java

@@ -964,7 +964,7 @@ public class HumanPlayer extends PlayerImpl {
     protected void selectCombatGroup(UUID defenderId, UUID blockerId, Game game) {
         updateGameStatePriority("selectCombatGroup", game);
         TargetAttackingCreature target = new TargetAttackingCreature();
-        game.fireSelectTargetEvent(playerId, "Select attacker to block", target.possibleTargets(null, playerId, game), false, getOptions(target, null));
+        game.fireSelectTargetEvent(playerId, addSecondLineWithObjectName("Select attacker to block", blockerId, game), target.possibleTargets(null, playerId, game), false, getOptions(target, null));
         waitForResponse(game);
         if (response.getBoolean() != null) {
             // do nothing

Mage.Sets/src/mage/sets/journeyintonyx/OppressiveRays.java

@@ -69,7 +69,7 @@ public class OppressiveRays extends CardImpl {
         Ability ability = new EnchantAbility(auraTarget.getTargetName());
         this.addAbility(ability);
 
-        // Enchanted creature can't attack or block unless its controller pays 3.
+        // Enchanted creature can't attack or block unless its controller pays {3}.
         this.addAbility(new SimpleStaticAbility(Zone.BATTLEFIELD, new CantAttackBlockUnlessPaysAttachedEffect(new ManaCostsImpl<>("{3}"), AttachmentType.AURA)));
 
         // Activated abilities of enchanted creature cost {3} more to activate.

Mage.Tests/src/test/java/org/mage/test/cards/requirement/BlockRequirementTest.java

@@ -0,0 +1,79 @@
+/*
+ *  Copyright 2010 BetaSteward_at_googlemail.com. All rights reserved.
+ *
+ *  Redistribution and use in source and binary forms, with or without modification, are
+ *  permitted provided that the following conditions are met:
+ *
+ *     1. Redistributions of source code must retain the above copyright notice, this list of
+ *        conditions and the following disclaimer.
+ *
+ *     2. Redistributions in binary form must reproduce the above copyright notice, this list
+ *        of conditions and the following disclaimer in the documentation and/or other materials
+ *        provided with the distribution.
+ *
+ *  THIS SOFTWARE IS PROVIDED BY BetaSteward_at_googlemail.com ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ *  FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL BetaSteward_at_googlemail.com OR
+ *  CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ *  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ *  ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ *  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ *  ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ *  The views and conclusions contained in the software and documentation are those of the
+ *  authors and should not be interpreted as representing official policies, either expressed
+ *  or implied, of BetaSteward_at_googlemail.com.
+ */
+package org.mage.test.cards.requirement;
+
+import mage.constants.PhaseStep;
+import mage.constants.Zone;
+import org.junit.Test;
+import org.mage.test.serverside.base.CardTestPlayerBase;
+
+/**
+ *
+ * @author LevelX2
+ */
+public class BlockRequirementTest extends CardTestPlayerBase {
+
+    @Test
+    public void testPrizedUnicorn() {
+        addCard(Zone.BATTLEFIELD, playerA, "Silvercoat Lion"); // 2/2
+
+        // All creatures able to block Prized Unicorn do so.
+        addCard(Zone.BATTLEFIELD, playerB, "Prized Unicorn"); // 2/2
+
+        // Silvercoat Lion should be forced to block
+        attack(2, playerB, "Prized Unicorn");
+
+        setStopAt(2, PhaseStep.POSTCOMBAT_MAIN);
+        execute();
+
+        assertGraveyardCount(playerA, "Silvercoat Lion", 1);
+        assertGraveyardCount(playerB, "Prized Unicorn", 1);
+    }
+
+    @Test
+    public void testPrizedUnicornAndOppressiveRays() {
+        addCard(Zone.BATTLEFIELD, playerA, "Plains");
+        addCard(Zone.HAND, playerA, "Oppressive Rays");
+        addCard(Zone.BATTLEFIELD, playerA, "Silvercoat Lion"); // 2/2
+
+        // All creatures able to block Prized Unicorn do so.
+        addCard(Zone.BATTLEFIELD, playerB, "Prized Unicorn"); // 2/2
+
+        castSpell(1, PhaseStep.PRECOMBAT_MAIN, playerA, "Oppressive Rays", "Silvercoat Lion");
+
+        // Silvercoat Lion has not to block because it has to pay {3} to block
+        attack(2, playerB, "Prized Unicorn");
+
+        setStopAt(2, PhaseStep.POSTCOMBAT_MAIN);
+        execute();
+
+        assertPermanentCount(playerA, "Oppressive Rays", 1);
+        assertPermanentCount(playerA, "Silvercoat Lion", 1);
+        assertPermanentCount(playerB, "Prized Unicorn", 1);
+    }
+}

Mage/src/mage/abilities/effects/common/combat/CantAttackBlockUnlessPaysAttachedEffect.java

@@ -47,9 +47,9 @@ public class CantAttackBlockUnlessPaysAttachedEffect extends PayCostToAttackBloc
 
     public CantAttackBlockUnlessPaysAttachedEffect(ManaCosts manaCosts, AttachmentType attachmentType) {
         super(Duration.WhileOnBattlefield, Outcome.Detriment, RestrictType.ATTACK_AND_BLOCK, manaCosts);
-        staticText = attachmentType.equals(AttachmentType.AURA) ? "Enchanted " : "Equipped "
+        staticText = (attachmentType.equals(AttachmentType.AURA) ? "Enchanted " : "Equipped ")
                 + "creature can't attack or block unless its controller pays "
-                + manaCosts == null ? "" : manaCosts.getText();
+                + (manaCosts == null ? "" : manaCosts.getText());
     }
 
     public CantAttackBlockUnlessPaysAttachedEffect(CantAttackBlockUnlessPaysAttachedEffect effect) {

Mage/src/mage/game/combat/Combat.java

@@ -263,7 +263,7 @@ public class Combat implements Serializable, Copyable<Combat> {
                 }
             }
             if (mustAttack) {
-                // check which defenders the forced to attck creature can attack without paying a cost
+                // check which defenders the forced to attack creature can attack without paying a cost
                 HashSet<UUID> defendersCostlessAttackable = new HashSet<>();
                 defendersCostlessAttackable.addAll(defenders);
                 for (UUID defenderId : defenders) {
@@ -501,6 +501,12 @@ public class Combat implements Serializable, Copyable<Combat> {
                         UUID attackingCreatureId = requirementEntry.getKey().mustBlockAttacker(ability, game);
                         Player defender = game.getPlayer(possibleBlocker.getControllerId());
                         if (attackingCreatureId != null && defender != null && possibleBlocker.canBlock(attackingCreatureId, game)) {
+                            // check if the possible blocker has to pay cost to block, if so don't force
+                            if (game.getContinuousEffects().checkIfThereArePayCostToAttackBlockEffects(
+                                    GameEvent.getEvent(GameEvent.EventType.DECLARE_BLOCKER, attackingCreatureId, possibleBlocker.getId(), possibleBlocker.getControllerId()), game)) {
+                                // has cost to block to pay so remove this attacker
+                                continue;
+                            }
                             if (creatureMustBlockAttackers.containsKey(possibleBlocker.getId())) {
                                 creatureMustBlockAttackers.get(possibleBlocker.getId()).add(attackingCreatureId);
                             } else {
@@ -734,6 +740,21 @@ public class Combat implements Serializable, Copyable<Combat> {
             if (creatureForcedToBlock == null) {
                 break;
             }
+
+//            // check if creature has to pay a cost to block so it's not mandatory to block
+//            boolean removedAttacker = false;
+//            for (Iterator<UUID> iterator = entry.getValue().iterator(); iterator.hasNext();) {
+//                UUID possibleAttackerId = iterator.next();
+//                if (game.getContinuousEffects().checkIfThereArePayCostToAttackBlockEffects(
+//                        GameEvent.getEvent(GameEvent.EventType.DECLARE_BLOCKER, possibleAttackerId, creatureForcedToBlock.getId(), creatureForcedToBlock.getControllerId()), game)) {
+//                    // has cost to block to pay so remove this attacker
+//                    iterator.remove();
+//                    removedAttacker = true;
+//                }
+//            }
+//            if (removedAttacker && entry.getValue().isEmpty()) {
+//                continue;
+//            }
             // creature does not block -> not allowed
             if (creatureForcedToBlock.getBlocking() == 0) {
                 blockIsValid = false;
@@ -765,7 +786,7 @@ public class Combat implements Serializable, Copyable<Combat> {
 
             }
             if (!blockIsValid) {
-                sb.append(" ").append(creatureForcedToBlock.getLogName());
+                sb.append(" ").append(creatureForcedToBlock.getIdName());
             }
         }
         if (sb.length() > 0) {

Mage/src/mage/players/PlayerImpl.java

@@ -2043,6 +2043,9 @@ public abstract class PlayerImpl implements Player, Serializable {
 
     @Override
     public void declareBlocker(UUID defenderId, UUID blockerId, UUID attackerId, Game game) {
+        if (isHuman()) {
+            setStoredBookmark(game.bookmarkState());
+        }
         Permanent blocker = game.getPermanent(blockerId);
         CombatGroup group = game.getCombat().findGroup(attackerId);
         if (blocker != null && group != null && group.canBlock(blocker, game)) {