TLDR: This is a fully updated modern scales list post MH2, slightly biased towards a local meta
What is modern scales?
Scales, centered around Hardened Scales is a strong midrange aggro deck with some combo potential. Over the years it has seen many variations from explosive Mox Opal based versions (pre-banning), to green-black builds, to more recent mono-green/green-red/green-white versions thanks to Zabaz, the Glimmerwasp. Though opinions may differ, the current green-white version of the deck may be the most resilient and competitive yet! Some say that hardened scales is currently under-represented in the current metagame due to the difficulty of the deck (warning: there can be a lot of math involved for counters), but it can be very rewarding to master.
The game plan
Generally what you want to be doing with this deck is creating a formidable board state ideally through use of key cards such as Arcbound Ravager, Hardened Scales, and The Ozolith. Each of these three cards can be seen as the deck's "engine". Modular creatures enter, and then are pumped as the game goes on. You can go wide with multiple mid-sized creatures, or you can go all in, creating a huge Inkmoth Nexus to take out your opponent in one single swing.
Card choices
_The engine: _ Arcbound Ravager, Hardened Scales, The Ozolith. In an ideal game, you want to see at least one of these cards. All of them will add crazy amounts of counters to your board, and are must-answer threats for your opponent. Keep them protected (for ravager, you may need to sacrifice it to move the counters around. That's fine).
_Value: _ Esper Sentinel Steel Overseer Zabaz, the Glimmerwasp Hangarback Walker Urza's Saga. Each of these cards gives you something you want. Esper Sentinel provides card draw, is very good in the current modern metagame, and works very nicely with counters. Steel Overseer, while slow, can provide you with many counters, especially when paired with Hardened Scales. Remember to protect it! Zabaz, the Glimmerwasp gives us extra modular triggers which is great for Arcbound Ravager, and gives us a way to kill our own artifacts, which can actually be helpful to release the counters (onto The Ozolith, or VIA modular). A big Hangarback Walker can be very difficult for the opponent to remove without exile, and can be an excellent target to sacrifice to Arcbound Ravager, as it creates more delicious thopters to feed to the beast. In addition, it can pump itself when you don't need it for blocking. Urza's Saga is the deck's toolbox. Any one or zero cost artifact can be found, which makes it extremely versatile. Need more mana? Springleaf Drum. More chump blockers? Animation Module. Protection? Welding Jar (which I don't use currently). Not to mention that saga can grab us The Ozolith or one of our many one mana modular threats.
_Finishers: _ Walking Ballista Inkmoth Nexus. If your opponent somehow manages to survive your army of creatures with counters, either of these is a game ender. Pumping them with any counter creator can be absolutely devastating. Ballista will hit the opponent straight in the face with unblockable damage, while inkmoth floats over your enemies to deal lethal in poison.
_Protection: _ Blacksmith's Skill. Instead of simply sacrificing a creature when it's about to die, skill can keep them on the field. One advantage of this card over Snakeskin Veil or Welding Jar is that it can protect your lands, namely Urza's Saga!
_Consistency: _ Ancient Stirrings. Some versions of this deck use Ingenious Smith while others choose stirrings, like this one. Stirrings can find lands in addition to artifacts which is why it's here. One mana to find almost anything you could possibly need? Excellent. Sometimes I remove Steel Overseer in favor of more of these for a lower curve.
_The mana base: _ Something I've always liked about this deck is that it doesn't require fetch lands to function. With just enough white mana producers to consistently cast Esper Sentinel and Prismatic Ending, we can usually take under three damage per game to fix our mana. The tiny splash of red is for zabaz' ability, which can be useful. Other versions of the deck choose to go more into red to use things like Goblin Bombardment.
Edit 28/01/22 Esper Sentinelx4 added as an excellent source of card draw, as well as a couple Steel Overseer for support (great sentinel synergy), and Blacksmith's Skill for an exile-heavy meta
