First off, Mask of Restrict is a decent Side Deck option against the latest tribute-stun archetype - True Kings/Shinryu. Just like how it stood in Monarch's way in earlier formats, it is a the Dimensional Barrier to any deck wanting to Advance Summon. You may recall that 3rd-4th place deck of the Malaysia Asia Qualifers recently, had a Zoodiac-Invoked-Artifact player side a playset of Mask of Restrict. (link)
Speaking of which, Mask of Restrict is probably appreciated by Invoked players more than any other decks, since it doubles as an anti-side measure as well. To escape the lockdown of Merkabah the Invoked, opponents are looking for cards that don't start a chain, so Merkabah the Invoked can't perform a negation. Baiting out the effect is always an option, but things may either end up not working your way, or you end up losing a card as payment for the negation. Kaiju is a popular reliable method to take out Merkabah the Invoked and even Elysion the Invoked. Of course, Lava Golem and Santa Claws are additional options, but Kaijus has always been the most commonly seen.
Mask of Restrict interferes with such plans, preventing the Special Summon of a Kaiju monster and protecting your board. Merkabah the Invoked can fend off Interuptted Kaiju Slumber on its own
and cost your opponent at least two cards to get rid of it.
Additionally, The Invoked archetype constantly faces the challenge of Artifact Lancea after sidedecking. In addition to interuptting a fusion summoning process, it might even force a fusion summon to be performed using cards in hand, resulting in a -3 since Eidolon Summoning Magic can't recycle itself, it also ward off Merkabah the Invoked's negatation tactics.
Artifact Lancea, unlike the other Artifacts, can tribute itself from the hand to use its effect. Hence, there isn't a need to special summon it onto the field during your opponent's turn, to use its effect, making it a very effective and unexpected hand trap. It replaced Imperial Iron Wall for quite some time now, for a plethora of reasons.
- Imperial Iron Wall can be easily taken out by Spell/Trap removal, and on top of it all, being a continuous trap means Zoodiac Drancia can take it out as well, making it less of a threat against Zoodiac-Invoked builds.
- Being a hand trap, it can still be useful when The Invoked player goes first, leaving the opponent with the option to chain its effect from the hand.
- Hand traps has always been a tougher threat to dodge or avoid, and even if Solemn Strike manages to catch it in time, it is a costly 1500LP.
Mask of Restrict is a reliable option for players to consider, especially The Invoked players. I like how cards in your opponent's hand, that were supposedly useful in a matchup against you, can wind up to be dead when Mask of Restrict is active.
Being a powerful floodgate to stop Master Peace further cements its position in the Side Deck. It will probably take your opponent by surprise too, as I believe it can be quite a shocking (anti-)side to other meta decks, like Zoodiac.