The first circuit Mack chose to carve in his body was the timer circuit. The first one he learned.
"I hope I'm choosing wisely."
His firm hand grabbed his dagger and like a man doing a surgery his head came extremely close to his left hand observing the minute details of his skin.
The tip of the blade touched the skin slightly and blood started to leave the small cut but Mack's gaze did not change a bit and slit the dagger over the skin of his left thumb.
Mack was carving very small runes over the thumb of his left hand.
And the runes were the same as the timed activation runes he first learned. But with two small differences....
The circuit multilayered design.
And the time for activation was almost one second from Earth.
Mack carved the rest of the runes and cleaned the residual blood from the cuts and finally could see a rune circuit pattern over his fingerprint on the left thumb.
It looked like a sand clock from Earth with a hexagram around. Small yet beautiful.
The hexagram was responsible for the circuit overlapping and the runes carved inside it formed a symbol of a sand clock.
Mack didn't delay pondering over the beauty of such a symbol and directly focused on activating it.
He could not lose too much time, or else he risked damaging the rune with his passive inhuman healing.
If the rune was not activated while the blood was still on the cuts it would just heal normally and disappear forever.
Mack focused his mind on that circuit and tried to activate it. But was hard for him. His Essence density was too huge and his will not strong enough, it was like trying to lift a car using only one finger.
Three long minutes later and the rune finally started to blink in red light.
Mack, covered in cold sweat, opened his eyes and could finally see that all his efforts until now finally paid off.
The rune was now a perpetual rune. Using the essence inside Mack's body to continually blink at each second.
~sigh~
"It worked!"
[Congratulations]
"All thanks to you. That overlapping circuit rune didn't exist on the cube. Even being as simple as an 'odd' hexagram I would never have guessed."
[The merit is all yours. As I said already. Information is the only thing I can provide you]
"Thanks anyway"
[...]
"Now to the real hard part."
Said Mack, looking at several circuits draw on the ground.
The circuit he carved in his hand was useless alone.
And around him, in a radius of more than 20 meters, not a single patch of grass could be seen.
The ground was brown and full of carved runes. And in the middle of all those runes a man and a cube.
Mack looked at the various prototypes he drew over the days and could not choose one. All of them seemed insignificant. With no great damage output.
He needed one to use in battles. That was the only reason he spent all those days researching and learning and practicing how to carve runes.
Most of them were useless in battle. Only three of them had a slim potential.
Mack devised these three circuits by himself because the cube had no circuits with battle purpose.
The biggest problem was he was not sure they would work or not.
The first one was very simple. It made all the Essence in a radius of 1000 meters congregate in a radius of 10 meters around the circuit. These 10 meters would have 100x more essence than the normal environment.
This was inspired by the trick he saw his former 'NPC' master doing during the battle in the first days.
The essence saturation would increase by a hundred times and would look like gravity itself was increased by 100 times for anyone in that 10 meters radius around the circuit. Just like the second trial on this tower.
It was good for stopping the enemy or defending but had not much attack power. No mage would die from this. But they would be stopped and had a hard time doing anything.
Mack looked at the other two circuits. One of them was just like a mage fireball.
And the other was an Essence blast. Essence would be compressed at a small point and move forward at a very fast speed.
Those two had much more attack power but Mack didn't have many hopes for them. They were the most complex of the three. The fireball one being the most complex.
If one stopped to think about the three circuits they were actually very similar in principle. The first one only condensing essence and making it denser in a radius of 10 meters. The second one did the same at a smaller point and then applied propulsion and made that condensed point to move forward. While the third one did the same as the two before but converted part of the Essence to fire.
Mack looked at the three of them and chose to test the harder one first. The fireball circuit.
He did have hopes that it would work. But not many hopes. He was an amateur after all.
Mack walked to the circuit draw on the ground and grabbed his dagger and made a cut in his index finger. A deep one.
Blood dripped on the ground and Mack raised his index finger above the lines of the circuit and now blood was falling on the circuit lines.
Mack was redrawing the runes on the ground using his blood.
Half a minute later a bloody circuit was drawn on the ground.
Mack came to the side of the circuit, crouched outside of it, and touched one of the lines with his left thumb.
He could now activate runic circuits outside his body. But only the ones made with his own blood. And only ones with that hexagram, the multilayered hexagram design.
The runes on the ground blinked red.
And then nothing more could be seen.
More exactly..... Mack went blind.
"What a heck just happened!"
Mack only saw white. No explosion. No fireball. Not even fire!
"Dammit! did I converted too much essence to fire?"
Mack fell on his butt, and the circuit on the ground stopped working.
He was still blind.
But he could not care for that at all. He knew his body would eventually heal. He was concerned about his new circuit.
"A failed experiment. At least I can blind myself now."
'Wait!'
"Maybe I can use that? Like a flash grenade from Earth?"