In this rule

Historical Rules · 25 July 2025

Rule 701.20c

Official source text from the 25 July 2025 Rules release

Permalink

A card that is currently revealed may be revealed again. Example: Telepathy is an enchantment card that reads “Your opponents play with their hands revealed.” Silvergill Adept is a creature card that reads, in part, “As an additional cost to cast this spell, reveal a Merfolk card from your hand or pay {3}.” A player may reveal a Merfolk card from their hand to pay the additional cost of Silvergill Adept even if that card is already revealed due to Telepathy’s effect.

Find this number in the current Rules