Conditions: having 7~8 €/$ available for you to buy a 4-pack of Forge in the Steam store (using a -75% coupon), not trade banned and a 5 €/$ game in mind and not having Forge in your inventory at the moment.
Procedure: I give you my -75% coupon, you buy the 4-pack and activate it, receiving one copy in your library and three inventory copies. You trade me the inventory copies for a 5 €/$ game you request me to buy. It's possible that you can activate it and receive four inventory copies so your copy can be used for trading, I do not know and take no responsibility should this not be the case.
Conditions: having 7~8 €/$ available for you to buy a 4-pack of Forge in the Steam store (using a -75% coupon), not trade banned and a 5 €/$ game in mind and not having Forge in your inventory at the moment.
Procedure: I give you my -75% coupon, you buy the 4-pack and activate it, receiving one copy in your library and three inventory copies. You trade me the inventory copies for a 5 €/$ game you request me to buy. It's possible that you can activate it and receive four inventory copies so your copy can be used for trading, I do not know and take no responsibility should this not be the case.
This screenshot should explain why I'm doing this.
Edit: Because of the way this works out I will need you to have enough +rep to trust you.