The answers and debate here got me interested enough to spend some wildcards to test it out.

I don't like the Arena-specific keywords. As opposed to acorn stuff, where there's probably a pretty close answer that we can figure out and roll with it; with the Arena ones, they feel like they should have comprehensive rules but just don't, and with these niche scenarios you can't be sure whether you should trust the game is handling it correctly or if they just didn't care to implement it properly.

Anyway, all that to say the answer doesn't make sense and is unsatisfying. As Gidge said, Reezug doesn't say "in addition" and just changes the card directly into an artifact. Except for sorceries (and presumably instants), apparently. Search for Blex became a sorcery artifact card that behaved exactly like a sorcery, including binning itself after resolution.

I'll leave the question up for a bit if ye want to discuss it further, and so that when I get the time I can test that I can't have it otherwise enter the battlefield.

Arena-specific question. I don't think I have the cards to test it RN.

Reezug, the Bonecobbler can turn both sides of a MDFC creature into an artefact. I've done this before with a Sheoldred  ^Flip which I paid to flip over into an artefact that didn't do anything. I've also seen it happen to a Grist, Voracious Larva  ^Flip which transformed into an artefact with loyalty abilities.

What happens if you turn a Blex, Vexing Pest  ^Flip into an artefact card and then cast Search for Blex  ^Flip?

Yeah, so they'd still have infinite hand size with the Reliquary Tower—but, with that sneaky li'l -2 just waiting in the wings until Winter.

Haha, thanks very much! I've often wondered if I'd made an impression on any of ye big-name folks over in the Q&A section. That makes me happy. ^^

Right-o! Fair enough.

In my head for some reason "you have no max hand size" == "your hand size is ∞", so it would have just been ∞-2 until Winter came along. Oh well!

I control a Locust Miser. My opponent plays a Reliquary Tower. I play a Winter, Misanthropic Guide with exactly 4 card types among cards in my graveyard.

Does the Miser's ability reduce my opponent's maximum hand size after Winter has reset it? Or does the Reliquary Tower negate the Miser's ability somwhow due to them being applied in timestamp order? I.E. Is my opponent's maximum hand size 3 or 1?

Do hand size adjusting effects (± one) and hand size setting effects (== thirteen) apply on different sublayers?

Cheers!

I have delirium, and I control a Shifting Woodland. An opponent has a Reliquary Tower which entered after my Shifting Woodland. If I activate the Shifting Woodland's ability to become a copy of Winter, Misanthropic Guide, does that opponent have no maximum hand size, or [Winter 3-] hand size?

Hardened Scales can 'see' itself and all other things dying simultaneously die, that's correct. But unfortunately unlike Teysa, this doesn't matter, because the Hardened Scales needs to still be on the battlefield for its replacement effect to apply to the ability. It's not enough for it to just have been there when the ability triggered.