More thoughts on how and when to use Icon relationship rolls in a 13th Age game.
At the Beginning of the Campaign or Story Arc
At the beginning of a campaign or a major new story arc, characters could make Icon rolls to see if they have recently been doing the work of one of the Icons (or if they have been working against one of the Icons, for that matter). On a 5 or 6, the character has just returned from a mission of this nature.
On a 5, the character gives up one of their recoveries until they can take an extended rest, as the mission was particularly strenuous and the character has had little time to rest.
When the character rolls a 5 or 6, their Icon (or an opponent of the Icon) has given the gift of a magic item to the character in exchange for their service. If the GM feels this is too generous, or has already used this as a means of introducing a permanent magic item, you can always shift the reward to something like a rune.
Each player that rolls a 5 or 6 should tell the group what kind of mission they were on and why it was important, as well as how it either helped or hindered the Icon with which they have the relationship. A character with a conflicted relationship should explain why the Icon isn't totally negatively disposed towards them, if they acted against them, or why the Icon is still cautious about the PC, if they aided the Icon.
When the PCs Save Someone That They Don't Have to Save
Any time the PCs go out of their way to save characters that they have no other interest in saving, roll an Icon relationship roll. On a 5 or 6, the character has saved someone important to the Icon (or their enemies) that is now in the PCs debt.
The character is now a contact that will answer questions in their area of expertise without any check or payment required. The player should note the name of the contact and where they live, and if the PC makes the trek to visit that contact, they will answer questions as best they can.
On a 6, the character not only is willing to be a contact for the PC that saved them, but they have somethingof immediate use to the PCs that they are willing to part with (consumable magic item, mounts, a secret passage out of town, etc.).
When the PCs decide to retreat from an encounter, have all of them roll an Icon relationship roll. If the any of the players end up with a 5 or a 6, the "cavalry" from the Icon's forces (or their enemy's forces) arrive and helps the PCs fight free of the bad guys.
On a 5, this is an arduous, hard fought retreat, and the PCs should narrate how they managed to get away. They must spend either a Daily or Recharge power that they can't use until they get an extended rest, spend at recovery, lose a single use item, or lose a number of hit points equal to what they might normally receive from a recovery.
On a 6, the retreat is well covered, and the PCs get away without any harm or expenditure of power or health. In either case, the party will not suffer a campaign setback if they received a backup from their allies.
When the PCs are Investigating or Researching Information
When the PCs are researching a vital bit of information, or are investigating a circumstance, roll an Icon relationship check before they begin their research or investigation. On a 5 or 6 the Icon or their proxies have decided to make the answer obvious to the PCs.
On a 5, the PCs run into an agent of the Icon, or if the Icon is feeling especially generous, a magical sending reaches them. The PCs will receive the location of where they might find the answer to their questions, whether it might be an ancient stone wall with the answer inscribed, an oracle, or something else that will distribute information to the PCs, but the trip should not be without some form of peril, even though the information is revealed without any difficulty once the PCs reach the proper site for the answer.
On a 6, the agent of the Icon will directly hand the answer to the PC without any further check.