There have been several threads about how the dark pacts, as written, seem to make the Lurker more of a quasi Herald/Guardian due to the ease with which they can be exploited. I won't rehash the exploits here except to mention what I consider another flaw: once you have more then one pact you can gain a power token using one pact and then spend it using the rules on a different pact. For instance, if you have both the Soul Pact and Blood Pact, you can drain some stamina with the Blood Pact and then turn around and use that power to prevent a stamina loss via the Soul Pact.

Anyway, various solutions have been posed (the best in my mind so far being the simple "an investigator can't spend power on the turn you gain it"), however they don't address the issue mentioned above. In addition, there is still the issue of what to do with Soul/Blood pacts if final combat should happen.

After tossing ideas around I started to consider the following: what would happen if power tokens were associated with a pact and the pacts could not be kept when final combat begins. To be more precise:

Gaining Power

• If an investigator gains a power token from a game mechanic (e.g. reckoning card) and they have at least one dark pact, they must place each power token gained on a pact card that they have. Once placed on a pact, a power token can't be moved to another pact.
• When an investigator has a dark pact and gains power as a result of that pact, all power tokens gained go on that same pact card.
  
• If an investigator gains a dark pact and already has power tokens, all power tokens they currently have are immediately placed on the pact they just gained.

Spending Power

• When spending a power token you must follow the instructions for the pact it belongs to.
  For example: if you have Soul Pact with two power tokens and also a Bound Ally pact with no tokens, then you cannot spend a power token as $1, instead it can only be used as a clue or to prevent a stamina loss.
• You cannot spend a power token if the pact it belongs to is exhausted.
  Yes, I know this re-interprets the card as written. If you wish, you could instead use "don't spend power on the turn it was gained", although that requires more book keeping. Exhausted is easy to track and also forces to think about when you drain for power (since you will block the use of existing power on that card).

Final combat: debts are due

• When the AO awakes, immediately discard all Soul and Blood Pacts held by investigators. Each power token on a pact discarded this way is added to the AO sheet. Each power token added requires one additional success in order to defeat the AO.
  This is meant to be similar to how Rhan Tegoth works with drained stamina.

I've used these in a couple of games already and find them easy to implement (though I've yet to go to final battle). All in all it makes the pacts much more thematic - investigators were taking pacts earlier, adding power for future use, and then worrying about getting hit with the effects of a reckoning. In particular, not spending power tokens from an exhausted pact forced me to have to plan when I would get the power and thereby hold it on to it longer … thereby increasing the sting when certain reckonings came up.

The main issue I have with this is that it renders the Bound Ally's power for money ability nearly useless. And to be honest, I don't really see the multi-pact effects as a problem. A player with two or three pacts is definitely far more powerful than if those pacts were spread around, but the reckoning cards are set up to pretty thoroughly brutalize anyone who does that.

I am a fan of the "can't spend power with an exhausted pact" thing though. As you say, it has approximately the same effect as "can't spend power the turn you get it," but isn't quite as inelegant.

I don't have Lurker yet (and probably won't for a while, sadly) but your example would be easily fixed with a house rule that we've employed: That Stamina/ Sanity PAYMENTS don't count as a loss, because you're doing so by choice. So anything that says 'prevent X Stamina/Sanity loss' can't be used to abuse instances where you're willingly sacrificing them to get something in return, such as casting a spell. In this instance, you're willingly paying that Stamina to gain power, so we would rule that you can't lessen that amount, because it is not another source damaging you, but an action you yourself chose to do.

subochre: When coming up with this plan I was aware of the limitation for bound allies and power. Frankly, it didn't bother me because I have yet to use a power token for $1 ... they are much more useful as a clue or to block a stamina/sanity loss. That said, you could always add one more clause: "you can transfer one (or more) power tokens from a refreshed pact to any other pact. Then exhaust the pact that received the power". That way Bound Ally pacts can gain power but still need to wait to use it.

Personally though, bank loans are a much more preferred way to get $. That said, i can see using a pact to avoid defaulting on a bank loan.

Mighty Maltim: My intent was not to say that one pact could block the draining of stamina/sanity for another pact ... in this I agree with you: the draining constitutes a payment and cannot be blocked (by spending power tokens). No such things as a free lunch.

My point was that if power is pooled and you have many pacts, then one power token gets very powerful, with up to three different uses (and of these, the most useful, spending as a clue, can be triggered if just one of you pacts is not exhausted). The goal is to tie a power token to the way it was gained.