How to cast magic spells with runes?

and is there any rune that I can cast death spells with it?

Not in the Elder Futhark, where the runes are more about empowerment, like the Tree of Life, they follow a progression of personal development.

However in the Younger Futhark, Algiz inversed becomes Yr, the “death rune” although that’s an oversimplification as it represents the entrance to the underworld and the word means Yew (the berries of Yew trees are poisonous, but Yew is a sacred tree).

In the vein of “too much of anything becomes toxic” you can combine runes into a overabundance that becomes smothering maybe adding Yr as a final destination. Add Raidho for travel. You could put the two on a picture of your enemy of Yr and Raidho meaning “My enemy travels to the underworld”. Maybe add Laguz (water) for speed and Thurisaz for power.