I hope this solution is as easy as I think it is...

THE ISSUE AT HAND

some people were heavy believers in SteemMonsters and have bought a ton of card... more than what they need to play. Perhaps they aren't even players. They would like to see those cards put to use and see their investment working for them.

THE FIRST IDEA... DELEGATION/RENTING...

This is perhaps the end game for a lot of large holders of cards... to put them to use as sorts of Mercernary cards... cards that will fight someone else's war for money... but are never owned by that person.
This idea is being pushed by co-founder Hive account@aggroed a bunch as well. And we may see it sometime after tournaments begin... let's say early next year is to be able to allow your cards to be used by another player while those cards remain safely in your possession with 0% of a bad actor or theft. It's a solid idea and it will certainly change the game up a bit and allow people with less money to get huge rewards in a given week and facilitate upward mobility.

SECOND IDEA: The "In the meantime" proposal
Hive account@nealmcspadden has basically proposed to users he is willing to give users cards in turn for the rewards they earn for the first 60 days and then when they work them off they get them. So they can play without money and put in the time.
https://steempeak.com/steemmonsters/@nealmcspadden/steemmonsters-want-to-play-without-spending-money-here-s-your-chance

This solution requires a lot of trust because he is giving access to a Posting Key... which is all that is needed to Transfer Cards away from one account into another.

On the blockchain the moment they leave his account there is no recource whatsoever.
All Hive account@steemmonsters is able to do is perhaps ban that account or those cards from being used in game play. But then what happens to other game creators will they now have that imposition put on them? What about markets... will PeakMonsters be required towards a burden of work if this is the case and be pushed into non-neutrality?

A POSSIBLE SOLUTION BY Hive account@jarvie ... GUEST LOG IN

A SOLUTION THAT IS MAYBE EVEN MORE THAN IN THE MEANTIME
I think both Hive account@aggroed and Hive account@nealmcspadden would love it and probably Hive account@yabapmatt may appreciate because it MAY not take too much effort.

1. Create steemmonsters login for a separate account
   ... No we're not talking using any STEEM keys involved for this login.
2. On this login allow (trust) SteemMonsters to save your POSTING key (cryptographically and safely)
3. Allow this login to ONLY interact with game play, Nothing else.
   No transfers, no sells, no merging cards... ONLY play games.
4. One step better is allow whoever has the posting key to select what this "guest login" can or can't do.
5. Then you can safely and easily give that Login to any friend you want... the most they'll do is be really bad at the game and hurt your stats. But you gave them access to play.

I think it's a beautiful solution. I'd go right now to create accounts for all my nephews and put solid teams in there for them to play. Heck i'd give access to random strangers and have zero worry they transfer or sell or do anything stupid.

POSTING KEY SHOULD BE ABLE TO...

1. Create a guest login (name and password)
2. Decide what actions that login can do
   (default and perhaps only action is battle actions)
3. Possibly they can also allow the guest to do the following

• Open packs
• Accept quest rewards or season rewards
• Buy cards for this account (with guests' own steem account money)
• Merge Cards (somewhat dangerous)
• Sell cards (dangerous)
• Transfer cards (dangerous)
• Transfer cards TO a designated account (not dangerous)

BETTER THAN DELEGATION??

Both have good use cases but I think personally i'm more interested in getting new players into the game and hooking up friends and family than I am selling rights to use my card for a week. One option gets this game more users... but truth is i'll likely use both options.

THE WORK

Hive account@yabapmatt will have to tell us what's involved
If Hive account@peakmonsters were to do it i'd have an idea of how it'd all go down. First we'd only allow battle actions to start with and not even give other options for the time being and expand as we saw interest.
The biggest effort is safely guarding the posting key because as it stands https://peakmonsters.com doesn't even know that key. However if we used SteemConnect then it can give rights to use posting authority for that user for an extended time... so that could be a valid option. However this issue is easier for SteemMonsters because they already have the posting keys of most all the users. Only some have removed trust and used Keychain. Setting up a login system with differing rights however it's something all programmers do all the time is determine what authorities a certain user has on a website.

That's the Minimum Viable Product and it doesn't need a fancy interface to begin with. Just an interface that allows a posting key holder to create a login with a password.

RECAP

Let me repeat that this guest at no point should have access in any way to ANY steem key and yet should have access on SteemMonsters.com to play to their hearts content.

The owner of the account has to trust SteemMonsters with their Posting key or uses a nice secure and trustless system to be given and encrypt the posting key... but be able to have it used. Let's remind people that I'm guessing the majority of people input their posting key into SteemMonsters.com already. While many of us don't and use keychain instead.

And of course I want people to come up

USE THIS MARKET

Of course https://peakmonsters.com is a beautiful awesome place for buying and selling cards and packs. And as of today there is a whole slew of small updates that made it even better.