Why can I not hire heroes???!!!
Are the members of your guild posting heroes higher then plus three levels above your level? If so that’s probably why. Honestly with the mass amount of mercs needed with city watch, and endless surge… be nice perblue and @Polaris remove the limit of hire and just replace the merc perk for three levels higher (which been asking for awhile to increase to plus five on here, but at this point in the game think be best for new players and old just to remove the limit all together at this stage of the game) with extra guild coins per hired hero instead … my opinion at least.
Maybe you don’t have enough gold
If you are referring to Surge, you could also be trying to attack an already cleared section, which doesn’t allow for merc hiring until the wave has been reset and it is untouched again. But it could also be the level issue, like mentioned.