You must also reveal all face-down spells and permanents you control if you leave the game or the game ends
However, given the context, I would keep the Angel and the Tiger

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Test of Endurance is an impressive white enchantment for four mana that can allow one's high life total to become an easily achievable alternative means of winning a game
(If a permanent with a stun counter would become untapped, remove one from it instead.) You don't choose a target for Snaremaster Sprite's ability at the time it triggers
The decision to make a new designation 'banned as Companion' appeared to weigh heavily on the designers, based on Gavin Verhey's article - adding sub-lists increases complexity and the chance that players will bring a card in a slot it's not supposed to