These are used, in combination with outer sleeves, for double-sleeving
That artifact will stop being an Equipment and become unattached from any creature it was attached to
This lets you slam down the Herald seconds before certain doom, giving you a chance to cast it in response to practically anything your opponent could do
As far as generic removal and one of the best Polymorph effects in MTG, Chaos Warp is one of reds best ways to remove permanents
As such, this is more interesting as a card that you snag a copy of for personal use, or keep on your radar as something to pick up whenever you see it underpriced for long term gains
That's a play pattern from the past, but still representative of the blowouts you can pull off with this merfolk