What if I have an instrument of the bards and I can cast this spell once per day for “free”.  Given I still have to concentrate on it I’m thinking of using it on the spore Druid’s zombie.  He used animate dead a lot and it would make the zombie go from ac 8 to 16.  He might stay alive a little longer.  Can you think of other creatures a party may have I could cast it on?  A summon like summon elemental? 

Maybe this would be best cast on the Palidan’s steed or greater steed. 

When casted from The Staff of the Woodlands is concentrating still needed. I never used one of these staves before

I beg to differ the spell states nothing about stat bonuses, shields or any magic items. It simply stats the AC can’t be below 16. So if you are just wearing clothes the base AC that you would have is 16 from the spell then you would add any other bonuses from items IE shield magic and stats. 

so just stating with the spellbase of 16 now with  dex bonus of +3 (17) then the AC would be 19 if not higher (Shield, rings, cloaks staff, or other spell buffs).

if I’m wrong please tell me. I’ve been playing since 78 even the PHB back then as well as now it states “skin becomes bark like” so wearing any armor Splint would be useless.