Equalizer Modifier is one of those rule sets that changes how every battle feels. Instead of worrying about which unit has low health all units suddenly become tanks at the start. This makes fights longer and also gives more time for abilities to matter. In this kind of battle damage over time and scaling effects become very important. Even units that normally die fast can stay alive long enough to do their job. Because of that Equalizer Modifier rewards smart combos more than just raw stats.

Modifiers

Equalizer - The initial Health of all Units is equal to that of the Units on either team with the highest base Health.
Equalizer is an excellent modifier for Water element. Since Water element focuses on damage, and magic damage on top of that, the modifier synergizes really well with the element's natural strength. Since health is taken cared of in this modifier, what you want is damage. The higher the damage you can take on the battlefield, the less your enemies will benefit from the increase of health from the modifier.

Good Abilities to use in Equalizer Modifier

Inspire - Gives all friendly Units +1 Melee attack
Inspire becomes stronger in Equalizer Modifier because in this modifier, damage s everything. Since all units have high health, melee attackers have more time to keep swinging every round. That extra +1 melee damage keeps stacking in value the more Inspire units you have. This is especially useful when using multiple melee units in the same team. You are basically increasing the total damage output across many turns. Because of increased melee damage Inspire can slowly overwhelm the enemy team.

Sneak - Targets the last Unit on the enemy Team instead of the first Unit
Sneak is very dangerous in Equalizer Modifier because players usually focus too much on the front. Since everyone becomes a tank no one expects an attack from the back. Enemies usually places the strongest damage units in the back since it's the safest position. Sneak units take advantage of that and start removing damage dealers early. Once the enemy loses their backline damage their tanky frontline becomes easier to handle. This makes Sneak a strong surprise tool in this Modifier.

Tank Heal - Restores a portion of the Unit in the first position's health each round
Tank Heal benefits a lot in Equalizer Modifier because healing scales with health. Since all units now have high health the amount healed every round also becomes bigger. This makes frontline units very hard to remove without strong damage. Even poison or chip damage becomes less effective when healing is this strong. Tank Heal also works well in long battles which Equalizer Modifier usually creates. Because of this teams with Tank Heal often gain a big advantage.

Affliction - When a Unit with Affliction hits a target, it has a chance of applying Affliction on the target causing it to be unable to be healed.
Affliction is very important in Equalizer Modifier because it counters healing. In this battle the one who has Tank Heal has usually the higher chance of winning. You take that chance out by applying Affliction on their tank. Once healing is blocked even high health units start falling. This ability also becomes more valuable the longer the fight goes. Stopping one heal can change the entire battle.

Last Stand - Gains increased stats if it's the only Unit on the team alive
Last Stand becomes scary in Equalizer Modifier because of the increased base stats. Since the stats benefitting from Last Stand are the current ones the bonus gets larger. The benefit from the Equalizer Modifier gets multiplied by half which still results in huge numbers. A last remaining unit can suddenly become very hard to defeat. This is even stronger if the final unit already has good damage. Last Stand can turn a losing battle into a comeback.

Battle Summary

It was a bad thing that my tank got poisoned before the battle even start because of the Chaos Jailer's Ambush poisoned attack. Even so, Equalizer modifier helped me since everyone is a tank in this modifier. That means one poison is not enough to keep my units down. Overall, I still have the higher damage so I was able to come out on top. They also have a weird setup which made this battle easier than it should be.

To see the full battle, you can click this link:
https://splinterlands.com/battle/sl_4c1e5df38aca8f0115a12aa5958e4806

Equalizer Modifier creates longer battles where ability synergy matters but I believe damage is king. Even when my tank got poisoned early the extra health allowed my team to stay alive. That gave me enough time to use my higher damage and slowly win the fight. The enemy also had a weird setup which made their damage less effective. For newer players, I think you just need to remember one thing in Equalizer modifier, put the highest damage you can get and you can win.