In the past, the main concern was random, expensive, old Reserved List cards, which are comparatively easy to counterfeit
You only untap one creature, but thats plenty exploitable with cards like The Infamous Cruelclaw, Roxanne, Starfall Savant, and any other creatures with valuable saboteur or attack triggers you want to get multiple times a turn
"into their owner's hand" is here for a reason
An attacking or blocking creature that phases out is removed from combat
Wingmantle Chaplain doesnt make wall tokens, but it makes Bird tokens equal to the number of defender creatures you control
Then you can discard two cards at the beginning of your first main phase to return this to your hand from your graveyard, which is card disadvantage naturally but with madness, lands, discard triggers like Archfiend of Ifnir, and loads more, it's got value