When does summoning get "locked out" in Darkroot?

[roymaster45]

(This is on the Switch version of the game, but I suspect it's a similar issue across all platforms.)
I have a friend who's been trying to help me with co-op in some of the trickier areas + bosses of the game (as well as certain optional bosses or challenges). However, we keep running into a problem where I'm unable to see his summon sign even when we're both human... seemingly because I already defeated the boss(es) for that area. For example, I've already killed Taurus Demon = no summoning anywhere in Undead Burg. Defeated the Bell Gargoyles? Cool, now you can't summon him in the Undead Parish.

At this moment, there are three main bosses or mini-bosses I haven't beaten in Darkroot Forest + Basin: Sif the Wolf, the Hydra, or Havel. Does anybody know if it will still be possible for me to summon my friend somewhere in Darkroot Basin to help with these? Or do we need to go somewhere completely new like Sen's Fortress and backtrack from there?

[Komarimaru]

Unless my memory is faulty, you can't summon in an area where you've cleared the boss already. So to summon, they, or yourself, have to be near a boss not yet killed.

[Squirel_squire]

You can summon for Sif after the door opened by Artorias' Crest. Havel and Hydra are not bosses, so no help there.
If you want to try, I have some videos:

Havel: https://www.youtube.com/watch?v=B_HxIQnmOHk

Hydra: https://www.youtube.com/watch?v=rwL3PjA3Sls

[Celsius]

You can't summon in the Basin to kill the hydra if you already killed the Moonlight Butterfly.
Havel is in the Taurus Demon area and can't summon if he is dead.
Sif has its own area which is after the Crest gate.

[Krivvin]

If you summon into the Darkroot Forest, there is a jump down into the Basin that would allow you to co-op against the Hydra after killing the Moonlight Butterfly. But, you and your co-op friend would need to make the jump.

After making the jump, you will not be able to go back up into the Forest. So after killing the Hydra, your co-op friend would need to leave your world.

I don't think you can access Havel's Tower from the Darkroot side. I think that Havel can only be fought from the Undead Burg side. I might be wrong though. But, that's what I remember.

[roymaster45]

OK, makes sense. Thanks for the input everyone!

One follow-up question: I kill the Basin's Black Knight a while back and unlocked the bonfire in the cave leading to Valley of Drakes. I haven't killed any of the non-respawning enemies there yet, but since VoD doesn't really have a "boss" to speak of (at least according to the wiki), does anybody know whether my friend and I would be able to summon each other in from there?

[Krivvin]

Unfortunately, I don't think Valley of Drakes can be co-oped. Too bad. It's an intense little area.

[grobdor]

Only areas that have a boss can be summoned in so unfortunately some places like valley of drakes will only ever be traversed alone. Stay alert, and praise the sun!

[Arcade Bumstead]

Sometimes I feel like I'm the only person who plays this game solo.
The absolute state of "the gaming community".