This is my first tab so please be kind :S
Tuning EADG
Intro
G-7---5--------------|
D---5----------------|
A--------5h3---5---3-|
E-----------5h3--3---|
From then on its just
G--------------------|
D--------------------|
A-5---3--5h3---5---3-|
E---3-------5h3--3---|
[ Tab from: https://www.guitartabs.cc/tabs/t/thin_lizzy/showdown_btab.html ]
Then just before and during the chorus, it will change the hammer-on section into fiddly
For those bits keep in key of D and keep to the style and have fun in those gaps
For the build in before the time change just keep playing...
A-33333333333333333
...till the it plays the chorus faster to the end of the track
Please Rate :D