Avalanche Two-Step is a synergy ability in Final Fantasy VII Rebirth, used by Barret Wallace with Tifa Lockhart as a synergy partner. It costs three synergy charges each, deals physical damage to one target, and extends the stagger duration on a target.
In the ability's animation, Barret and Tifa both launch toward a target and perform a flurry of attacks from Barret's gun-arm and Tifa's fists.
Obtained[]
Avalanche Two-Step is unlocked on Barret's folio, and costs 10 SP. It is available at party level 2.
Use[]
Avalanche Two-Step costs three synergy charges each on first use, and four on subsequent uses. When used on a staggered foe, it will lengthen the duration they are staggered for, and increase damage they receive. This can be an excellent way to deal more damage to an already-vulnerable enemy during stagger, but the length of the Avalanche Two-Step animation means it should be timed to apply early on in the stagger duration. The best outcome is when Avalanche Two-Step itself staggers the enemy.
Barret is particularly strong in building an enemy's stagger gauge, enabling him to stagger enemies quickly. Both his Focused Shot attack, and Bonus Round, enable him to build stagger quicker on enemies. As Tifa's Unfettered Fury and Focused Strike can also build stagger quickly, combined the two form a lethal pair in quickly staggering and then bursting down an enemy, meaning they benefit greatly from then using Avalanche Two-Step right when staggering the foe.
Tifa is unique in her ability to increase the stagger damage multiplier, as her Unbridled Strength and True Strike abilities allow her to do so at a rate no other party member can match. This means that extending stagger duration can allow her to boost this damage even further over the length of a longer stagger. However, it also means that Tifa is tied to the animation of Avalanche Two-Step for its duration, and therefore is unable to increase the enemy's stagger multiplier while she and Barret are performing the ability. As such, though the effect is something Tifa can take great advantage of, timing is crucial to achieve maximum benefits, or it should be achieved with other party members performing a different synergy ability.
Barret can also achieve this effect with Purrfect Shot with Cait Sith or with Sweet-and-Sour Salvo with Aerith Gainsborough. Tifa can achieve the effect with Relentless Rush with Cloud Strife, Call of the Wild with Red XIII, or Cyclonic Kick with Yuffie Kisaragi.
As an alternative, or addition, to extending stagger duration through Avalanche Two-Step, 
Stop can be cast on a staggered enemy, as 
Stop will pause and thus lengthen stagger.