The fourth miniature in the five-day reveal is shown with a grenade, and Games Workshop says the full Warhammer 40,000: Armageddon boxed set will be unveiled at 19:00 BST tomorrow.
The company describes Grots as battlefield scavengers used for dangerous tasks such as mine clearing and drawing enemy fire, framing the new figure as one that has "found" or stolen the stikkbomb.
The update follows earlier reveals of shooting, sneaking and stabbing Grots, leaving one final Gretchin model to complete the week's Xenos Identification Chart before the Armageddon set showcase.
Will the Armageddon reveal feature one giant starter set, or just the four announced battalion boxes?
Why is the new Astra Militarum box 50% more expensive than the other Armageddon faction sets?
With Commissar Yarrick's return, how will his new rules honor his legendary and supposedly final stand?