NERF IT.
Now, let me qualify my answer.
There are three possible times summon is used in PK:
1.)Your group is larger than their group.
2.)Your group is roughly equal to their group.
3.)Your group is smaller their group.
In case #1... why add insult to injury? They're already running for the hills. Hunt them down the old fashion way or just take their relic, or something obnoxious like that.
In case #2... why mess up a decent fight by summoning? If you pick off one guy from their group and gank them, then their whole group runs away to some no summon area. You went from having a good, clean fight to only getting one kill. IMO it rewards whoever wants to be lame first if they lack the skill and prep to win fair.
In case #3... maybe I can see this being used as the underdog. But still, if your opponents have summoners, they can just spam it on you, then you just run. Frustrating.
Ultimately, my preferred vision for SK is an environment where everyone fights and dies proportionally more, and battles are fought relatively closely in size versus ganking and the occasional massive group conflict. Summoning discourages group combat, definitely. It also makes people more bitter than dying normally for the most part, because they didn't even have a CHANCE to fight. Nobody wants to prep for hours and then caught by a random lucky first summon when they're walking along one day and get killed. If you're going to die, at least die fighting.
edit: I forgot about the gate idea. My proposal is to make auto summon make you completely immune, but make gate SIGNIFICANTLY easier to land.
edit: Summoning also makes the MUD less fun for players in general. I don't think many people feel terribly proud when they summon someone to their giant group and just rape them, unless they really hate the player/char with serious viciousness. And nobody likes dying to summon ganks.
Additionally, summon widens the gap between the casual player and the serious player. Summon is a reason why it's hard to bring PCs new to PK along with you, because they can be picked off so easily with summon. Unless you work really hard to enchant your suit, hunting for a target who's summoning you is incredibly difficult (assuming you're good at your job, you only get closer with each second). For a casual player, they might have 10-20 willpower enchants: stuff that comes with their armor, some accessories, and maybe a few actually enchanted items. If they die, they still won't bother getting all that much more (they think they'll only die again) and of course they'll probably just get summoned and owned again depending on the makeup of their enemies.
This instills a feeling of hopelessness, bitterness, and frustration in newer players. They're inexperienced enough that even if somebody enchanted their things for them for willpower, they'd probably die to some other event. They'll die often. That's part of learning. But if you're going to die, dying to summon is the WORST way to go.
Everyone hates summon.
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