In late summer and early fall, ‘Spatlese’ monkshood gives you airy spires of  light lavender-blue flowers that darken over time. The strong, upright form and soft color make it an excellent background plant in the border, especially with fall's bright yellows and oranges. It prefers part shade but will take full sun as long as the soil's moist. 

Aconitums are commonly known as monkshood, because the upper
sepal of each flower resembles the hoods of medieval monks. They
attract a variety of butterflies and moths, and are the primary food
source for Old World bees. Another common name, wolfbane, refers to the
poison made
from this plant's roots, which was used to tip hunting arrows.
Medicinal (and poisonous) uses of this plant date back to Roman times.
What's the difference between a medicine and a poison? Dosage.