Canât your friend fly to you? Or you can use a Fly-Along flight mount and transport them to the delve. Placing a summon stone would not help when 2 people are already required for a summon.
I mean they can just⌠go there? If they refuse to do that then theyâre not a very good friend I have to say - or donât really want to play.
Importantly, do remember that you can enter a delve and have it scaled to 1 player while you wait, and once the other player arrives it automatically scales to 2. You can just start.
I havenât really tested it, but doesnât the Delve get âlockedâ once you speak to the NPC at the entrance to start it? Wouldnât otherwise be âoptimalâ to clear a Delve solo up to the final boss, then invite 4 friends and get them in for the final boss only and give everyone max rewards without doing the instance?