Acid Splash 4e FAQ FAQ
Why does Acid Splash attack Reflex instead of touch AC in D&D 4e?
The D&D Portal 4e conversion attacks Reflex because 4e does not use the 3e/3.5e touch-Armor-Class system as the normal way to resolve spell attacks. Attack powers instead roll against AC, Fortitude, Reflex, or Will. Reflex is the most natural defense for Acid Splash because the power represents an incoming magical acid projectile that a creature can avoid, and the official 4e Sorcerer power Acid Orb also attacks Reflex. The change is therefore an edition conversion rather than a renamed version of touch AC.
One of the biggest mistakes in cross-edition conversions is preserving a familiar rule term even after the destination edition has changed the underlying resolution system. Acid Splash used a ranged touch attack in 3e and 3.5e, but 4e organizes attacks around four defenses rather than normal AC plus touch AC. The Portal conversion therefore keeps the intent of the older mechanic—an attack that is more about avoiding contact than penetrating armor—while expressing that intent through Reflex, a defense that actually exists within the native 4e attack framework.
D&D 4e uses AC, Fortitude, Reflex, and Will
Attack powers 
D&D Portal - Attack Roll Combat rule Attack Roll is a combat rule used by attacks,
damage, defenses, or turn order. Full link: https://dnd-portal.com/rules/combat/attack-roll/ in 4e normally specify one of four defenses: armor class 
D&D Portal - Armor Class Combat rule Armor Class is a combat rule used by attacks,
damage, defenses, or turn order. Full link: https://dnd-portal.com/rules/combat/armor-class/, Fortitude, Reflex, or Will. The attacker rolls against that defense and the hit or miss result determines what part of the power occurs.
This structure replaces several older resolution patterns. A 3.x spell might use a touch attack, allow a saving throw D&D Portal - Saving Throw D20 test rule Saving Throw is a d20 test rule used to resolve
uncertain outcomes during play. Full link: https://dnd-portal.com/rules/d20-tests/saving-throw/, or require a separate spell-resistance check, while a 4e attack power D&D Portal - Attack Roll Combat rule Attack Roll is a combat rule used by attacks,
damage, defenses, or turn order. Full link: https://dnd-portal.com/rules/combat/attack-roll/ generally packages its primary accuracy check into attack versus defense.
Adding armor class D&D Portal - Armor Class Combat rule Armor Class is a combat rule used by attacks,
damage, defenses, or turn order. Full link: https://dnd-portal.com/rules/combat/armor-class/ back into the conversion would create a fifth defensive calculation that is not part of the normal 4e power framework. Using one of the existing defenses therefore produces a cleaner and more edition-native result.
Reflex fits an avoidable acid projectile
Acid 
D&D Portal - Acid Damage type Acid is a damage type used by attacks,
spells, class features, resistance, immunity, and vulnerability. Full link: https://dnd-portal.com/rules/damage-types/acid/ Splash is represented as a projectile of magical Acid D&D Portal - Acid Damage type Acid is a damage type used by attacks,
spells, class features, resistance, immunity, and vulnerability. Full link: https://dnd-portal.com/rules/damage-types/acid/ traveling toward a creature. Conceptually, the target is trying to avoid contact with the projectile rather than relying primarily on toughness or mental resistance.
Reflex therefore matches the intended interaction better than Fortitude or Will. It also preserves some of the identity of the older ranged touch attack, where heavy armor was not the main obstacle to landing the spell.
That does not mean Reflex is mathematically equivalent to armor class D&D Portal - Armor Class Combat rule Armor Class is a combat rule used by attacks,
damage, defenses, or turn order. Full link: https://dnd-portal.com/rules/combat/armor-class/. The defenses are built differently and interact with different rules. The conversion preserves the concept of an avoidable magical projectile, not the exact numbers of the old system.
Acid Orb supports Reflex as a 4e design choice
Acid D&D Portal - Acid Damage type Acid is a damage type used by attacks,
spells, class features, resistance, immunity, and vulnerability. Full link: https://dnd-portal.com/rules/damage-types/acid/ Orb is an official level 1 Sorcerer 
D&D Portal - Sorcerer Character class A Charisma-based known-spell full caster whose Sorcery Points and Metamagic reshape spells in ways other casters cannot. Full link: https://dnd-portal.com/classes/sorcerer/ at-will spell that also represents a ranged projectile of Acid D&D Portal - Acid Damage type Acid is a damage type used by attacks,
spells, class features, resistance, immunity, and vulnerability. Full link: https://dnd-portal.com/rules/damage-types/acid/. Its attack is Charisma versus Reflex.
That official power provides strong evidence that Reflex is an established defensive target for this style of arcane Acid D&D Portal - Acid Damage type Acid is a damage type used by attacks,
spells, class features, resistance, immunity, and vulnerability. Full link: https://dnd-portal.com/rules/damage-types/acid/ attack in 4e. D&D Portal therefore does not need to invent a new defense or force the conversion to attack AC.
The comparison stops there. Acid D&D Portal - Acid Damage type Acid is a damage type used by attacks,
spells, class features, resistance, immunity, and vulnerability. Full link: https://dnd-portal.com/rules/damage-types/acid/ Splash does not copy Acid D&D Portal - Acid Damage type Acid is a damage type used by attacks,
spells, class features, resistance, immunity, and vulnerability. Full link: https://dnd-portal.com/rules/damage-types/acid/ Orb’s Ranged 20 distance, 1d10 damage die, or ranged-basic-attack feature. Reflex is used as part of the edition’s design language rather than as evidence that the powers are the same.
The target does not make a saving throw to avoid the initial hit
Players coming from later editions may expect a Dexterity or Reflex saving throw D&D Portal - Saving Throw D20 test rule Saving Throw is a d20 test rule used to resolve
uncertain outcomes during play. Full link: https://dnd-portal.com/rules/d20-tests/saving-throw/ against an Acid D&D Portal - Acid Damage type Acid is a damage type used by attacks,
spells, class features, resistance, immunity, and vulnerability. Full link: https://dnd-portal.com/rules/damage-types/acid/ projectile. The Portal 4e conversion does not use that structure for the initial attack.
The caster makes the attack roll against the target’s Reflex defense. If the attack meets or exceeds Reflex, the primary hit occurs and can trigger the adjacent splash damage. If the attack misses, the hit effect does not occur.
4e saving throw D&D Portal - Saving Throw D20 test rule Saving Throw is a d20 test rule used to resolve
uncertain outcomes during play. Full link: https://dnd-portal.com/rules/d20-tests/saving-throw/ have a different common role, especially for ending ongoing effects and conditions. They are not the standard replacement for the attack-versus-defense roll used by a power such as this conversion of Acid D&D Portal - Acid Damage type Acid is a damage type used by attacks,
spells, class features, resistance, immunity, and vulnerability. Full link: https://dnd-portal.com/rules/damage-types/acid/ Splash.
Why does the conversion not attack Armor Class?
Using AC would make physical protection a much more central part of resisting Acid D&D Portal - Acid Damage type Acid is a damage type used by attacks,
spells, class features, resistance, immunity, and vulnerability. Full link: https://dnd-portal.com/rules/damage-types/acid/ Splash. That would move the conversion farther away from the identity of the earlier ranged touch attack.
Reflex instead emphasizes movement, reaction, and avoiding the attack. It also places Acid D&D Portal - Acid Damage type Acid is a damage type used by attacks,
spells, class features, resistance, immunity, and vulnerability. Full link: https://dnd-portal.com/rules/damage-types/acid/ Splash alongside official 4e magical attacks that resolve against Reflex rather than against the target’s armored defense.
The choice is ultimately part of the homebrew conversion and is documented for that reason. It is not presented as an official ruling that “ armor class D&D Portal - Armor Class Combat rule Armor Class is a combat rule used by attacks,
damage, defenses, or turn order. Full link: https://dnd-portal.com/rules/combat/armor-class/ became Reflex”; it is a deliberate adaptation to the mechanics available in 4e.