Comments from the Finger: I think every class needs some stranger options. Thanks to Sleepy Magus, who helped out on this one
The god that you worship is bizarre, and forgotten to almost all in the realms of men. Gods of Slime are often nameless, churning deities of filth, possessing no temples and few if any worshippers. It is, therefore, a mystery wherefore their immense power originates. Scholars of divinity speculate that, perhaps, the Slime Domain naturally occurs as a result of other gods' waste. Or perhaps, oozes themselves, in spite of being unintelligent in every conceivable sense, still possess the capability to worship at some level, and therefore empower these nameless gods.
Slime Domain Spells
1st grease, ray of sickness
3rd acid arrow, enlarge/reduce
5th meld into stone, stinking cloud
7th blight, freedom of movement
9th cloudkill, contagion
At 1st level, you learn the acid splash and poison spray cantrips, which count as cleric cantrips for you.
Starting at 2nd level, you have resistance to acid and poison damage.
Additionally, when you cast a spell which deals acid damage to a target, it takes an additional 1d4 acid damage. If the target carries or wears either metal armor or a metal shield, it must make a Dexterity saving throw. On a failed save, one metal armor or shield of your choice takes a permanent and cumulative -1 penalty to the AC it offers. Armor reduced to an AC of 10 or a shield that drops to a +0 bonus is destroyed.
This acid damage increases by 1d4 when you reach 5th level (2d4), 11th level (3d4), and 17th level (4d4).
Channel Divinity: Rebuke Ooze
At 2nd level, as an action, you can attempt to command an ooze you can see within 30 feet of you. This ooze must make a Wisdom saving throw or obey your commands for the next 24 hours, or until you use this Channel Divinity option again. An ooze whose challenge rating is equal to or greater than your level is immune to this effect.
While an ooze is under your command, you can use a bonus action on each of your turns to mentally command it if it is within 60 feet of you. You decide what action the creature will take and where it will move during its next turn. If given no command, the ooze does not act.
At 6th level, you can secrete slime from your skin and orifices as an action. For the next minute, you have advantage on checks against being grappled and, when a creature within your reach hits you with a melee attack, you can use your reaction to deal 3d6 acid damage to it.
At 8th level, you gain the ability to infuse your weapon strikes with divine energy. Once on each of your turns when you hit a creature with a weapon attack, you can cause the attack to deal an extra 1d8 acid damage to the target. When you reach 14th level, the extra damage increases to 2d8.
Starting at 17th level, you can use your action to summon a gelatinous cube to envelop your enemies. Choose a space you can see within 120 feet for the cube to appear. If you summon the cube into a creature's space, the creature is subject to the cube's Engulf and has disadvantage on the saving throw. You can command the cube as with your Rebuke Ooze feature.
The cube's maximum hit points are increased by twice your level, and, if cube calls for a saving throw, it uses your spell save DC instead.
The cube vanishes if it is reduced to 0 hit points, or after one hour. After using this ability to summon an ooze, you can't do so again until you finish a long rest.
Changelog: 8/27/16: Corrosive Touch: Reworded for clarity
Summon Cube: 120 foot range