Smash you head with a brick and walk away. Wormwood is bad. It tastes bad. It is like pure tannis. Unless you like the sides and back of you tongue covered in bitter as #$^*#@$(&# stuff along with with your throat being squeezed really hard, in that case give it a go. I used less than 1/8oz in a 6 gallon batch, in just under 2 years it is barley drinkable.
FWIW there is NO, I repeat NO, "extra effects" either. That was a medieval sales pitch that was used to sell booze that was really high ABV and tasted worse than a hot, flat, festering in the sun, BMC product.
You have been warned...