Veteran of the Depths
Most counter-accumulating creatures want you to send them into combat, where attacking and the inevitable trade do the bookkeeping. This one widens the trigger to the more abstract event: any tapping at all. Vigilance is irrelevant; what it wants is a reason to tap that isn't an attack, which means it pairs with anything that taps a creature for value: convoke costs, tap-to-activate abilities, the old crewing and exerting logic that arrived in later eras. Each tap is an optional counter, so a creature you tap repeatedly grows on a schedule your attackers don't control. The friction is that a 2/2 for four mana is asking a lot of patience before the body matters, and the counter only ever arrives one at a time. The result is a slow snowball that rewards a board built to tap things, not a card that does anything on its own turn it lands. It belongs to the wide family of "rewards being tapped" designs that quietly underpin tap-synergy decks, where the engine is the act of tapping rather than the creature being tapped.

