First, Build the Wrath of the Ancients bow. Click this link on how to do that.
Second, Go all the way up on the Clock Tower and look on the wall where you will see a mark. Shoot that using your bow to reveal the Broken arrow.
Third, you need to go to the launch pad area and wait until the rocket test is complete. Once the gate is open, run quick towards to your right and look up on wall where you will see a bring red light. Shot it using your bow and a big fire ball will comes out. Note: This bright light will disappear in a couple of seconds and if that happen you need to wait again for the rocket test countdown.
Fourth, Three Ritual Circles. First location, Between Clock Tower and Death Ray Trap. Second location, Between Double Tap and Spawn Area. And Final location, is on the Death Ray Trap. Note: This can be done in any order. Next is kind a hard so be patient. To activate this circles, you need to shot it while you are air born. To do this, you need to use the launch pad but make sure you have a lot of points because you will spend 500 each time you use. If you did this correctly, It will lead up with chime. Next, Go inside the circle and kill 5 to 10 zombies to collect souls. Do this on those two remaining.
Fifth, Go back to the tower and press action button and the mechanism will spin after its done, you will see a symbol. Next, Find and locate three fire place around the map and inside that. There are a symbol. Locations: Control Room, Samatha’s Room and Second level in Lower Courtyard near wonderfizz machine. After you find your right symbol, Go back to the three ritual circle and check which one is still leads up. Then, step inside again and kill zombie to reveal the lava. That lava need to reach to the fire place but take note that you can try three shots only each round and if you miss it or made a mistake, you need to start a new round and redo again. To bring this lava, Step inside and shot your bow where you want to bring it. Once this lava reach its destination, Fire place will be lead up and you can press action to reveal the part.
Sixth, Easiest step. go on the death ray trap and the fire ball will be almost in the floor. Just go below that and press action button and the fire ball will explode on the air and reforged arrow will be drop.
Last, Bring this reforged arrow on the basement and place it on the fire box. This box is located near the pyramid. Kill 15 to 25 zombies, once its done. Place your bow on that box and in a few seconds your new bow will comes up. Pick it up and there you have it.