Wasn't sure how to Double retain Karlssons contract via Yotes, to Toronto to reduce the cap hit to Tor.

SJ and AZ both decline.

A washed up 2nd rate low skill goon like Kassian doesn't fetch anything near that. Retention on Karlsson's monster contract for the 5 years left on it won't be cheap either. Muzzin is a cap dump, Holl and Robertson don't add much value and 2 late 1sts aren't nearly enough to make up for all that.

It will cost you a 1st to dump Muzzin's contract, it is no sure thing he is washed and could potentially play next season (he also has a NTC).

It will cost you a 1st for every year that you need someone to take on $5M in cap, that's 4.5 years.

Reimer would also cost around 1st or 2nd (especially if he peforms well before the deadline)

So that's basically seven high level picks before we even talk about Karlsson's value.

For retaining half, on Karlsson's contract fair would be three to four 1st rounders, one or two 2nd rounder, Robertson, Sandin, and Liljegren

It would be way too much.

Leafs aren't giving up 2 firsts and Robertson for that. He is not the type of dman we need anyway.

Might be getting a little carried away there but your last point is true.

I mean without a contract in place Karlsson went for 1st (Tim Stuetzle), 2nd (Zach Ostapchuk), Josh Norris (1st round pick), Chris Tienery (40 point scorer at the time), Dylan Demelo (20 point scorer), Rudolfs Balcers.

Karlsson is acutally looking better than when he was traded, the trading team wants 1/2 retention, and are asked to take on Jake Muzzin, I think you would have to give up the moon, especially for making a team retain ~$5M for 5 years.

3 1sts, 2nd, 3 prospects is a would have to be split up between SJ and Arizona and even then it wouldn't feel like either came out without a significant loss.

Your not taking into consideration the negative value in acquiring a 33yr old dman who has 5 more years on contract and a VERY extensive injury history. Yes he's playing very well so far this year but we're 15games in, whose to say he can even make it a whole season at this point. The fact he's played so well THIS year is the main reason any acquiring team would entertain a trade.
I would think looking at what the sharks got for Burns is a good guideline for EK, but add value due to slight age difference.
(For Burns -Steven Lorentz, goalie prospect Eetu Makiniemi, and a third-round pick in the 2023, they retained 34%)

In the end Karlsson isn't the player the leafs need to target anyways

We are in agreement, but my arguments for the high price is about that risk in particular.

His age is certainly a factor, but for a win-now team selling the house for a player who has returned to Norris caliber at 50% retention and offloading a negative contract a windfall split between two teams isn't out of grasp.

In regards to risk, remember the risk is shared by both teams. If that player is bought out by the Leafs within those 5 years, they can potentially extend a 5-year commitment even longer for the Coyotes and additionally burn 1/3 of a team's buyouts for a number of years. That's why no team would take 5 years 50% retained, ever unless they were given a top-line or top-pair player ++++.