Start removing logic that depends on a single opponent, as this (naturally) doesn't work in multiplayer games.

'OppLifeTotal' is now removed, and started removing 'OppPoisonCounters'.

forge-ai/src/main/java/forge/ai/ability/DamageDealAi.java

@@ -392,8 +392,13 @@ public class DamageDealAi extends DamageAiBase {
                     }
                     continue;
                 }
+            } else if ("OppAtTenLife".equals(sa.getParam("AILogic"))) {
+            	for (final Player p : ai.getOpponents()) {
+            		if (sa.canTarget(p) && p.getLife() == 10 && tcs.getNumTargeted() < tgt.getMaxTargets(source, sa)) {
+            			tcs.add(p);
+            		}
+            	}
             }
-
             // TODO: Improve Damage, we shouldn't just target the player just
             // because we can
             else if (sa.canTarget(enemy)) {

forge-game/src/main/java/forge/game/card/CardFactoryUtil.java

@@ -961,7 +961,17 @@ public class CardFactoryUtil {
         
 
         if (sq[0].contains("YourLifeTotal"))        return doXMath(cc.getLife(), m, c);
-        if (sq[0].contains("OppLifeTotal"))         return doXMath(ccOpp.getLife(), m, c);
+        if (sq[0].contains("OppGreatestLifeTotal")) return doXMath(cc.getOpponentsGreatestLifeTotal(), m, c);
+        if (sq[0].contains("OppsAtLifeTotal")) {
+        	final int lifeTotal = xCount(c, sq[1]);
+        	int number = 0;
+        	for (final Player opp : cc.getOpponents()) {
+        		if (opp.getLife() == lifeTotal) {
+        			number++;
+        		}
+        	}
+        	return doXMath(number, m, c);
+        }
 
         //  Count$TargetedLifeTotal (targeted player's life total)
         if (sq[0].contains("TargetedLifeTotal")) {

forge-game/src/main/java/forge/game/player/Player.java

@@ -301,6 +301,22 @@ public class Player extends GameEntity implements Comparable<Player> {
         return result;
     }
 
+    /**
+     * Find the greatest life total amongst this player's opponents.
+     * 
+     * @return the life total of the opponent with the most life.
+     */
+    public final int getOpponentsGreatestLifeTotal() {
+    	final List<Player> opps = this.getOpponents();
+    	int greatestLifeTotal = Integer.MIN_VALUE;
+    	for (final Player p : opps) {
+    		if (p.getLife() > greatestLifeTotal) {
+    			greatestLifeTotal = p.getLife();
+    		}
+    	}
+    	return greatestLifeTotal;
+    }
+
     /**
      * returns allied players.
      * Should keep player relations somewhere in the match structure
@@ -2407,6 +2423,10 @@ public class Player extends GameEntity implements Comparable<Player> {
             if (this.getLife() != life) {
                 return false;
             }
+        } else if (property.equals("IsPoisoned")) {
+        	if (this.getPoisonCounters() <= 0) {
+        		return false;
+        	}
         } else if (property.startsWith("withMore")) {
             final String cardType = property.split("sThan")[0].substring(8);
             final Player controller = "Active".equals(property.split("sThan")[1]) ? game.getPhaseHandler().getPlayerTurn() : sourceController;
@@ -2426,7 +2446,7 @@ public class Player extends GameEntity implements Comparable<Player> {
                 return false;
             }
         } else if (property.startsWith("hasMore")) {
-            final Player controller = "Active".equals(property.split("Than")[1]) ? game.getPhaseHandler().getPlayerTurn() : sourceController;
+            final Player controller = property.contains("Than") && "Active".equals(property.split("Than")[1]) ? game.getPhaseHandler().getPlayerTurn() : sourceController;
             if (property.substring(7).startsWith("Life") && this.getLife() <= controller.getLife()) {
                 return false;
             } else if (property.substring(7).startsWith("CardsInHand")

forge-game/src/main/java/forge/game/staticability/StaticAbilityCantAttackBlock.java

@@ -79,6 +79,12 @@ public class StaticAbilityCantAttackBlock {
                 && defender.equals(hostCard.getGame().getNextPlayerAfter(card.getController(), hostCard.getChosenDirection()))) {
             return false;
         }
+        if (params.containsKey("UnlessDefender")) {
+        	final String type = params.get("UnlessDefender");
+        	if (defender.hasProperty(type, hostCard.getController(), hostCard)) {
+        		return false;
+        	}
+        }
 
         return true;
     }

forge-gui/res/cardsfolder/c/chained_throatseeker.txt

@@ -3,7 +3,6 @@ ManaCost:5 U
 Types:Creature Horror
 PT:5/5
 K:Infect
-S:Mode$ Continuous | Affected$ Card.Self | AddKeyword$ CARDNAME can't attack. | CheckSVar$ X | SVarCompare$ LE0 | Description$ CARDNAME can't attack unless defending player is poisoned.
+S:Mode$ CantAttack | ValidCard$ Card.Self | UnlessDefender$ IsPoisoned | Description$ CARDNAME can't attack unless defending player is poisoned.
-SVar:X:Count$OppPoisonCounters
 SVar:Picture:http://www.wizards.com/global/images/magic/general/chained_throatseeker.jpg
 Oracle:Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)\nChained Throatseeker can't attack unless defending player is poisoned.

forge-gui/res/cardsfolder/h/hidetsugus_second_rite.txt

@@ -1,9 +1,9 @@
 Name:Hidetsugu's Second Rite
 ManaCost:3 R
 Types:Instant
-A:SP$ DealDamage | Cost$ 3 R | ValidTgts$ Player | TgtPrompt$ Select target player | ConditionCheckSVar$ X | ConditionSVarCompare$ EQ10 | NumDmg$ 10 | References$ X | SpellDescription$ If target player has exactly 10 life, CARDNAME deals 10 damage to that player.
+A:SP$ DealDamage | Cost$ 3 R | ValidTgts$ Player | TgtPrompt$ Select target player | ConditionCheckSVar$ X | ConditionSVarCompare$ EQ10 | NumDmg$ 10 | References$ X | AILogic$ OppAtTenLife | SpellDescription$ If target player has exactly 10 life, CARDNAME deals 10 damage to that player.
 SVar:X:TargetedPlayer$LifeTotal
-SVar:Y:Count$OppLifeTotal
+SVar:Y:Count$OppsAtLifeTotal.10
-SVar:NeedsToPlayVar:Y EQ10
+SVar:NeedsToPlayVar:Y GE1
 SVar:Picture:http://resources.wizards.com/magic/cards/sok/en-us/card88818.jpg
 Oracle:If target player has exactly 10 life, Hidetsugu's Second Rite deals 10 damage to that player.

forge-gui/res/cardsfolder/k/keeper_of_the_flame.txt

@@ -2,8 +2,6 @@ Name:Keeper of the Flame
 ManaCost:R R
 Types:Creature Human Wizard
 PT:1/2
-A:AB$ DealDamage | Cost$ R T | ValidTgts$ Opponent | CheckSVar$ X | SVarCompare$ LTY | NumDmg$ 2 | References$ X,Y | SpellDescription$ Choose target opponent who had more life than you did as you activated this ability. CARDNAME deals 2 damage to him or her.
+A:AB$ DealDamage | Cost$ R T | ValidTgts$ Opponent.hasMoreLife | NumDmg$ 2 | SpellDescription$ Choose target opponent who had more life than you did as you activated this ability. CARDNAME deals 2 damage to him or her.
-SVar:X:Count$YourLifeTotal
-SVar:Y:Count$OppLifeTotal
 SVar:Picture:http://www.wizards.com/global/images/magic/general/keeper_of_the_flame.jpg
 Oracle:{R}, {T}: Choose target opponent who had more life than you did as you activated this ability. Keeper of the Flame deals 2 damage to him or her.

forge-gui/res/cardsfolder/k/keeper_of_the_light.txt

@@ -2,9 +2,7 @@ Name:Keeper of the Light
 ManaCost:W W
 Types:Creature Human Wizard
 PT:1/2
-A:AB$ Pump | Cost$ W T | ValidTgts$ Opponent | TgtPrompt$ Choose target opponent with more life than you | CheckSVar$ X | SVarCompare$ LTY | SubAbility$ LightKeepersLife | StackDescription$ None | References$ X,Y | SpellDescription$ Choose target opponent who had more life than you did as you activated this ability. You gain 3 life.
+A:AB$ Pump | Cost$ W T | ValidTgts$ Opponent.hasMoreLife | TgtPrompt$ Choose target opponent with more life than you | SubAbility$ LightKeepersLife | StackDescription$ None | SpellDescription$ Choose target opponent who had more life than you did as you activated this ability. You gain 3 life.
 SVar:LightKeepersLife:DB$ GainLife | Defined$ You | LifeAmount$ 3
-SVar:X:Count$YourLifeTotal
-SVar:Y:Count$OppLifeTotal
 SVar:Picture:http://www.wizards.com/global/images/magic/general/keeper_of_the_light.jpg
 Oracle:{W}, {T}: Choose target opponent who had more life than you did as you activated this ability. You gain 3 life.

forge-gui/res/cardsfolder/r/roiling_horror.txt

@@ -10,7 +10,7 @@ SVar:TrigLoseLife:AB$ LoseLife | Cost$ 0 | ValidTgts$ Player | TgtPrompt$ Choose
 SVar:DBGainLife:DB$ GainLife | Defined$ You | LifeAmount$ 1
 SVar:X:Count$xPaid
 SVar:Y:Count$YourLifeTotal/Minus.Z
-SVar:Z:Count$OppLifeTotal
+SVar:Z:Count$OppGreatestLifeTotal
 SVar:RemAIDeck:True
 SVar:Picture:http://www.wizards.com/global/images/magic/general/roiling_horror.jpg
-Oracle:Roiling Horror's power and toughness are each equal to your life total minus the life total of an opponent with the most life.\nSuspend X-{X}{B}{B}{B}. X can't be 0. (Rather than cast this card from your hand, you may pay {X}{B}{B}{B} and exile it with X time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, cast it without paying its mana cost. It has haste.)\nWhenever a time counter is removed from Roiling Horror while it's exiled, target player loses 1 life and you gain 1 life.
+Oracle:Roiling Horror's power and toughness are each equal to your life total minus the life total of an opponent with the most life.\nSuspend X- {X}{B}{B}{B}. X can't be 0. (Rather than cast this card from your hand, you may pay {X}{B}{B}{B} and exile it with X time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, cast it without paying its mana cost. It has haste.)\nWhenever a time counter is removed from Roiling Horror while it's exiled, target player loses 1 life and you gain 1 life.