Ruleset List
Name
Description
Standard No modifications to the standard gameplay rules and mechanics.

There are no special tricks for this ruleset, so just work on making a balanced team.
Aim True Melee and Ranged attacks always hit their target.

Blind, flying, dodge are useless in this ruleset. Speed is still good, but only for firing first - not for dodging.
Armored Up All monsters get a +2 armor buff at the beginning of the game.

Try bringing cards with Rust to remove the added armor, or with Void Armor to use the added armor to protect against Magic attacks.
Back to Basics All monsters lose their abilities. Note: Summoner effects which give monsters abilities will still be effective.

The key here is typically the summoner. Lorna and Rathe work well as they protect your team. Magic damage also typically works better (except against Rathe).
Broken Arrows Monsters with ranged attack cannot be used. Note: Monsters with 2 types of attack which include ranged in their attacks, such as War Chaang, also cannot be used.

Since all cards are either Melee or Magic, abilities that target those attack types work better here (such as Demoralize, Silence, Void, and Void Armor).
Close Range Monsters with ranged attacks are allowed to attack in the first position.
Earthquake All non-flying monsters take 2 physical damage at the end of every turn. Note: Snared monsters are considered non-flying. Since the damage given is physical, it can be reduced to 1 if the monster has the shield ability.
Equal Opportunity All units gain the Opportunity ability which allows them to attack the unit with the lowest health on the enemy team.

Opportunity targets the card with the lowest health, and if there are >1 cards with equally low health it'll target the one in the earlier position. Use this knowledge to place cards wisely, as you have pretty high confidence which of your cards will die first.
Equalizer All monsters start with the same health, based on the highest health on either team. Note: Buffs and debuffs are done afterward so this is based on the base health.

Fill up your team as much as possible. You'd rather be the one who brings many cards who are all equalized up to a high health than the one bringing a big card with lots of health.
Even Stevens Only monsters with even mana costs may be used. Note: This rule does not apply to summoners.

Interestingly, a lot of the commonly used sneak monsters cost an odd amount of mana (3, for the most part). You can use this knowledge in the 'Even Stevens' ruleset (less likely to get sneak attacked).
Explosive Weaponry All monsters gain the Blast ability.

Reflection Shields is very important in this ruleset. Speed (Swiftness and Slow) are important as well. You can also place a Martyr card in the 2nd position as a sacrificial card to take advantage of this ruleset.
Fog of War All monsters lose the Sneak, Snipe and Opportunity abilities.

Fog helps tanks without Taunt take more focus fire. Cards like Pelacor Conjurer, Almo, Onyx Sentinel, and many more who you'd love to see targeted work great in this ruleset.
Healed Out All healing abilities are removed. Note: This applies to summoners too. Examples of healing abilities are Heal, Tank Heal, and Triage.
Heavy Hitters All monsters gain the Knock Out ability.
Holy Protection All monsters gain the Divine Shield ability which reduces the damage of the first attack received to 0.
Keep Your Distance Monsters with melee attacks may not be used. Note: Monsters with 2 types of attack which include melee in their attacks, such as War Chaang, also cannot be used.
Little League Only monsters and summoners which have a mana cost of 4 or less may be used.
Lost Legendaries Legendary monsters may not be used. Note: Legendary summoners are still available.
Lost Magic Magic monsters may not be used in battle. Note: Monsters with 2 types of attack which include magic in their attacks, such as Kralus, also cannot be used.
Melee Mayhem Melee monsters can attack from any position. Note: Abilities still take precedence.
Noxious Fumes All monsters are afflicted with the Poison debuff at the start of the game. Note: Monsters who have Immunity are not afflicted. Additionally, this is a one-time application, which means that monsters that are cleansed or resurrected will not be re-applied with poison by this rule.
Odd Ones Out Only monsters with odd mana costs may be used. Note: Summoners are not affected by this rule.
Reverse Speed Monsters with lower speeds will attack before monsters with higher speeds. Miss calculations based on speed will also be reversed.
Rise of the Commons Only common and rare monsters may be used in battles. Note: Summoners are unaffected by this rule.
Silenced Summoners Summoners do not give any buffs/debuffs.
What Doesn't Kill You All monsters gain the Enrage ability which multiplies their speed and melee attack by 1.5x rounded up. Note: The attack multiplier only affects melee units and no other attack stats.
Stampede Trample will be able to retrigger infinitely as long as the trampling monster keeps killing other monsters.
Super Sneak All melee monsters gain the Sneak ability.
Taking Sides No neutral monsters may be used.
Target Practice All ranged and magic monsters gain the Snipe ability.
Unprotected All armor is removed from monsters and one cannot gain armor. Note: Shield and Divine Shield are unaffected.
Up Close & Personal Only monsters with melee attacks can be used. Note: Monsters with 2 types of attacks can be used as long as they have a melee attack as well. An example would be War Chaang.
Weak Magic Magic hits armor first before hitting health.
Aimless All monsters have the Scattershot ability.
Amplify All monsters have the Amplify ability.
Ferocity All monsters have the Fury ability.
Going the Distance Only monsters with ranged attacks may be used.
Magic Reflect All monsters receive the Magic Reflect ability at the start of the battle. Enemy monsters that attack with magic receive damage back. Damage returned is equal to the damage of the attacker divided by 2, rounded up.

Magic monsters with the Reflection Shield ability do not take damage from reflected magic attacks. Note: The Amplify ability increases damage.
Return Fire All monsters receive the Return Fire ability at the start of the battle. Enemy monsters that attack with ranged attacks receive damage back. Damage returned is equal to damage of the attacker divided by 2, rounded up.

Ranged attack monsters with the Reflection Shield ability do not take damage from reflected magic attacks. Note: The Amplify ability increases damage.
Wands Out Only monsters with magic attacks may be used.
Thorns All monsters receive the Thorns ability at the start of the battle. Enemy monsters that use melee attacks receive damage back. Damage returned is equal to damage of the attacker divided by 2, rounded up.

Note: Melee attack monsters with the Reflection Shield ability do not take damage from thorns. Note: The Amplify ability increases damage.
Tis But Scratches All cards get the Cripple ability
Are You Not Entertained Allows the use of one additional Gladiator card in the match.
Born Again All monsters get the Rebirth ability.

Cards with Divine Shield work really well here, as well as Martyr.