Activate this card only if you have no cards in your Extra Deck and control a Tribute Summoned monster. Negate the effects of all face-up monsters on the field, while those monsters are face-up on the field, except Tribute Summoned monsters'. During your End Phase, if you control no Tribute Summoned monsters, send this card to the Graveyard.
How to Get
Negates the effects of all monsters on the field, except tribute summoned monsters.
You must control a tribute summoned monster.
Non-tribute summoned monsters you control are also negated.
As the name implies this card was made with Monarch support in mind. All monarch monsters want to be tribute summoned to gain advantage. The Monarchs Erupt will serve as disruption against enemy monster effects with your Monarch's effects not being negated. The Vassal's will also not be negated as their effects activate on-hand and in the graveyard when they are tributed.
While you have a tribute summoned monster on the field, special summon Mithra the Thunder Vassal from your hand. Activate The Monarchs Erupt to negate the effects of Non-Tribute summoned monsters on the field. Mithra's effect would attempt to summon a token to your opponent's field but fail because of The Monarchs Erupt's negation. Mithra can then be used as tribute fodder without giving your opponent resources.
Ancient Gear is an archetype heavy on tribute summoning. Another trait of Ancient Gear monsters is that they prevent your opponent from using spell/trap cards during battle. With the added monster effect disruption of The Monarchs Erupt your opponent would have a hard time getting effects off against you.