What, the devil?

Recently, my good friend Mary Anne sent me this mysterious picture of an octagonal coin that she found somewhere. She was wondering if it had ancient and benevolent Confucian messages on it, and at first glance it sure does not.

The first thing that catches the eye when seeing this coin is the large encircled character in the middle. It says "KILL."

The character on the right I knew said "ghost" or "demon." And on the left it clearly says "thunder" but under that is a weird one so I tried to look up the entire poem in an attempt to see if there was an explanation somewhere.

One clue was on the other side of the coin, (not pictured) which has the Eight Trigrams or 八卦(ba1 gua4), from the Book of Changes (易经 yi4 jing1). They are used for divination and other types of fortunetelling stuff I am not real clear on. So the coin was some sort of Taoist medallion or a replica thereof.

Searching for the second stanza in the poem (which I did because I recognized all four characters in it) led me to a Chinese forum where someone had discovered a similar coin and was wondering about its value. Turns out (according to this person anyway), that the coin is a Taoist talisman, inscribed with a spell to ward off evil. Which as a former D&D player and eternal fan of sorcery, real magicks, weirde shite, the occult, et cetera, I found to be really awesome.

I figured out that this coin is called 符咒钱 (fu2 zhou4 qian2), or "charmed money." AKA 避邪钱 (bi4 xie2 qian2) "Ward-against-evil money." Its purpose is not to be exchanged for goods or services like regular money, but rather to protect your very soul from possession by demonic forces. Which I suppose is technically a "service," but what I'm saying is, you can't buy a veggie dumpling with this thing.
In Chinese the full text reads as follows:
雷霆雷霆、杀鬼降精、斩妖除邪、永保神清。奉太上老君急急如令敕

lei2 ting2 lei2 ting2
sha1 gui3 jiang4 jing1
zhan3 yao1 chu2 xie2
yong3 bao1 shen2 qing1

feng4 tai4 shang4 lao3 jun1 ji2 ji2 ru2 lv4 ling3 chi4

The large words on the left middle and right say
"Thunder kills the demons"

Here is how I have translated this spell. Note that I have (masterfully) maintained the Chinese rhyming scheme of 1,1,2,1. (in this case ting, jing, xie, qing)

Sound of thunder, sound of thunder
Kills the ghosts, drives sprites asunder
Beheads the goblins, wards off evil
Forever keeps the soul from plunder.

Tai Shang Lao Jun says it is so.

Tai Shang Lao Jun is a Taoist deity and this line is apparently common in Taoist incantations.

It is interesting to note several things here. First, the repetition mark. On the coin, right side, there is the large character, then going left from top to bottom you see the first two characters and then two squiggles. That indicates repetition. I haven't actually seen a double repetition mark like that. But there it is, and it means to repeat the previous 2 characters. You can find the mark on the left side, below the fifth character. It looks like a "z" kind of. Anyway, there it indicates repetition of the previous character only.

The other parts to notice are the odd, ancient words for ghost, goblin and sprite, and evil. I will go into those at another time. Until then, think of this spell when you hear thunder. Perhaps it is best to recite it a few times as well... Now that there is a definitive English version you should be OK!