5th level Dark Shard Amulet of the Elder God

This amulet is fashioned from a single shard of resilient extraplanar material originating from the realm of your warlock patron. As you rise in power it's power grows.  Within its facets multiple eyes can be seen  When the warlock is 4th level a small tentacle can be seen sprouting from the shard.  An additional tentacle appears every other level until 12th level. While you are wearing it, you gain the following benefits:

• You can use the amulet as a spellcasting focus for your warlock spells.
• You can cast a cantrip that you don’t know. The cantrip must be on the warlock spell list. You can’t use this property again until you finish a long rest.
• A 4th level warlock can cast any 1st level warlock spell once per day.  Prior to any wisdom save d10 needs to be rolled, on a 1, you have disadvantage on the save.
• At 5th level the amulet acts as a +1 ring of protection, and consumes a point of wisdom when attuned. 

Notes: Bonus: Armor Class, Bonus: Saving Throws, warlock