Alright, I'm guessing you hate SCP-049 as much as I do.

Remember that Euclid and Keter difficulty chances are different and worse.

This for Safe

Here's what you have to do:

Step 1: Level 2 Key card on Fine --> Level 3 Key card

Step 2: Level 3 Key card on Fine, right before it finishes, save. When it is not level 4 Key card load the game.

Step 3: Level 4 Key card on fine --> 100% Level 5 Key card

I made a nice video for you :)