What's your experience with the guilds?, is being nice for you? in my case I'm very happy about my guild (Peakmonsters ALL I) all the players are being very active and we have the Quest Lodge at lvl 4 already, and all this without investing any DEC in it (It isn't needed in Peakmonsters guilds).
I used the discount once only but the extra 4% DEC is very welcome to buy some cards, potions and the like. I highly recommend to the peakmonsters users our guilds.