Dude.... German pilsner is great. I do have a few suggestions:
1) Skip the protein rest. It doesn't help anything at all and will likely destroy body and head retention. Not needed with 21st century malts. Plus skipping it will make your mash schedule way simpler. Also...
You don't need to do a decoction, but it really wouldn't hurt anything if you wanted to try it. Just decoct from beta to alpha amylase, from 140 to 148 F or something like that. Or throw in an acid rest at 100 F and then take that up to 148 F. You could also decoct to mashout from 148 to 170 F. But skip the protein rest at 122 F.
2) When gravity hits half of the OG (e.g., 1.060 turns to 1.030), then it's time to start the D rest. No need for ramp up, just get it in the 60s and keep it there for 3 days. You can keep the temperature up there even longer, for a week or longer if you want, with no ill effects. It just helps the yeast finish the job and clean up after themselves, which includes diacetyl, sulfur, acetaldehyde, or other "green beer" characteristics.
3) What's your water going to look like? For this style, I would recommend jacking up both sulfate and chloride to enhance both bitterness and malt. If you're not sure how much to use, start with a teaspoon of each and see how you like the result. Otherwise you can use software to nail the salt additions appropriate for the style.
4) How much yeast you using? Be sure to pitch a nice big starter. Maybe 2.5 to 3 quarts or liters would suffice. I wouldn't use any less than that. Keep those yeasty beasts happy and you'll be rewarded.
5) Personal opinion: I don't think the late Hallertau additions will do as much for you as people think. In my experience, Hallertau (and any noble hops) taste better the LONGER they are boiled, not shorter. Others might not agree with me and that's fine. If nothing else, consider the idea of using Hallertau and/or Perle for all your bittering, and skip the Magnum, if you want lots of noble hop flavor. I promise you, the noble hop flavors come through loud and clear even with just a single 60-minute addition and no later "flavor" additions. In theory this might be due to the lower alpha acid, which would require that you use a higher quantity of the hops to get the IBUs you want... and the noble flavor has no trouble hanging around for the entire boil and fermentation. You can also think about it this way... for a thousand years, breweries never boiled hops for any less than 30 minutes, and more often it was for hours. Late hopping is a 20th century concept. You want to brew a traditional German lager? Then brew as the Germans do.
My opinions, take them for what they're worth, maybe 3 cents.
Best of luck to you.