Howdy all! We're coming up to a level 19 raid-style boss this weekend, Kyuss the Walking Worm itself. DM has mentioned several times it's going to be an encounter with no punches pulled and all resources should be used. So, I just want to clarify and confirm what I can and can't with my SSI. Im the party healer, have been since level 1 as far back as 5 years ago, an artificer alchemist, Hjalmar Gunderson (link can be found in my signature box). I have stocked my SSI with cure wounds since it came online. So:

• I can use it the same turn as casting a spell with a casting time of an action (Edit: by getting my Homunculus or Tiny Servant to take the Use An Item action)? e.g. action is used to cast haste and bonus action to use SSI with the effect of cure wounds.
• A common tactic of this character is to cast sanctuary and then use the help action after that. I can also use SSI with breaking Sanctuary because it's 'using an item' rather than 'casting a spell', right? Im certain J-Craw did a Sage Advice stating just that, but can't find it since.

Are there any other cool interactions I've not mentioned? Thanks for your time.

Quote from ArntItheBest >>

No to your first bullet. You only have one action, and the SSI requires your action to use. You can however cast a spell with a casting time of a Bonus Action and use the SSI, as the SSI is not casting a spell, just producing a spell effect (language is specifically different from a spell scroll, as the spell scroll says you are using the scroll to cast the spell).

For Sanctuary, you can already cast spells on allies without breaking it. Now, if you used the SSI to cast Shatter, you are going to end Sanctuary because you are dealing damage to another creature. But so long as you are using Help or healing, you're golden.

 Oh boy, I really screwed up my initial post! I have always gotten my tiny servant or homunculus to use it using the Use An Item action since it is not a magic item. My Bad!!!