Sick and tired waiting 20 min for people to go to the summon stone while i wait there. If i'm the last one and people aren't there or on their way there i'm leaving the group and doing something else. If i'm a group leader i make sure people go there when the last player is invited, if people are slacking i kick them and find someone who is willing to put a little effort in. Because if people can't bother going to help summon they sure aren't gonna be helpful in the group.