“ This is an idea for a basic weapon which I have adapted partially into a fighter subclass. Let me know what you think, because if it's any good, I may post the subclass.
Double Bulwark Shield
Melee weapon (martial, shield)
Category: Items
Damage: 1d6 per hand, 1d4 together
Damage Type: Bludgeoning
Item Rarity: Standard
Weight: 6
When wielding the Double Bulwark Shield in two separate parts, you gain +2 to your AC, +1 per hand.
When wielding two separate parts of the Double Bulwark Shield, you can take an action to bring the two halves of your shield together. Your movement is halved as long as the shield is brought together. If you move or attack after bringing your shield together this turn, you receive a +3 bonus to your AC. If you don’t move or attack after switching this turn, you and an ally directly behind you receive a +5 bonus to your AC. This action is known as Steadfast.
Once the shield is brought together, you may take a bonus action to become Steadfast even if you attack this turn. However, you may not move or attack after becoming Steadfast.
Taking apart your shield is considered a free action.”
“ The party has found the source of the strange creatures roaming the countryside. The rift in this reality glows with a silver hue, rippling with the wind but never moving. They step through and are immediately assaulted with the scent of rotting meat, some have to muster all their strength not to vomit. Strange cries similar to the beasts the party had faced before can be heard in the distance. Looking around, they see they are in a forest of grey and red rather than the normal brown and green. The trees are sticky to the touch and writhe, perhaps to get away or perhaps as a warning.
The deeper the party goes, the more the forest seems to slither and move underfoot. The cries get closer and more numerous. Creatures lurk in the shadows, all the same color of their surroundings. Whatever the party came in here for, they had better do it fast.
The forest of flesh is waking up, and it is so very hungry.”
“ A city is being plagued by a swarm of winged mice. The vermin can get anywhere, and they can easily avoid their normal predators by simply flying away from them.”