Tombstone Soda gets two major fundamental changes across its additional Tiers, starting with getting agents back into the fight quicker than before. Not having Perks decay when downed is an absolute boon as well, making it just a matter of buying another Tombstone Soda instead of a few lost Perks whenever you’re down for the count.
Jugger-Nog’s new Tiers not only make agents better tanks at Tier IV with reduced armor damage, it also essentially gives them a second life at Tier V. Being brought down to 1 HP rather than 0 can be enough of a cushion to push out of a zombie horde, or serve as a turn of fortune after a devastating blow from an Elite enemy.
Speed Cola becomes a speedrunner’s dream at Tier IV by making barricade repairs and Mystery Box rolls faster, and gains some serious benefits at Tier V. Outrunning the horde but can’t reload or thin their numbers with hip-fire? Now you can thanks to this awesome upgrade.
Quick Revive gives agents the ability to quickly get out of a bad situation after reviving an ally at Tier IV, granting a 5-second speed boost to both players. As for Tier V, it instantly revives you if you can kill an enemy while downed. This, on top of Self-Revive Kits and Jugger-Nog, can give agents more chances at survival than ever before.
Stamin-Up adds another speedy benefit to Zombies at Tier IV: using equipment while sprinting, great for those looking to hit moving Tomahawk shots or toss Cymbal Monkeys while escaping big hordes. Tier V makes agents even quicker thanks to the removal of sprint slowdown, making them move at maximum speed whenever they decide to pick up the pace.
Elemental Pop gets a major buff to elemental damage at Tier IV, and receives a bit of an “Electric Cherry” twist at Tier V thanks to that new ability. Agents may want to wait until a magazine is fully expended to deal the most damage to nearby enemies while reloading… or find weapons with smaller magazine sizes to hit this damage maximum more often.
Deadshot Daquiri becomes more potent with two different damage buffs: a 10% critical damage increase at Tier IV, and a consecutive hit bonus at Tier V. The former upgrade is great all around, while the latter is most useful against Elite enemies that require multiple hits before they return to their grave.
Outside of the new Shatter Blast Mod, the various Weapon Mods have a similar theme throughout their Tier IV and V upgrades. Also, remember that these bonuses apply to whenever these appear through Elemental Pop, which might move them up on your “must upgrade list” if you use that Perk often.