Something that I've been meaning to do for a while is to compile a list of misspellings and grammatical errors I've noticed on various cards. Today, I have finally done so. Here is my list.
COMMON:
Abbysal scavenger
Abbysal = "Abyssal"
oppoent's = "opponent's"
Abyssal Viper
uppercase second word
Benediction
hers = "her"
Cleansing
by = "with"
Conjurer
by = "with"
Druid
by = "with"
Mithril mine
Enemy Quarry = "Enemy quarry" *
Preparations
Enemy Dungeon = "Enemy dungeon" *
Ranger
by = "with"
Retribution
hers = "her"
Saints-day
Saints-day = "Saints Day" or "Saints' Day"
Temple of light
holy = "Holy" **
* For most cards (Azure unicorn, Basilisk, Bloody moon, Bounty hunter, Magic well, Cultists, Earth elemental, Immolation, Kidnap, Lava spectre, Lightning strike, Mind control, Murderer, Obsidian gargoyle, Soul cleaver, Treacherous artifact, Valkyrie, Daemon, Implosion, Magic rift, Shadow unicorn) mention of an enemy facility has the facility's name in lowercase.
** In most other cases, keywords are capitalized and boldface in card effect text.