Unable tap vehicle
My opponent crewed his Luxurious Locomotive with all his creatures and I was unable to tap it with my Sterling Keykeeper before attacks, although it specifies that it can only not tap mounts (vehicles should be fine).
The game turned from maybe winnable to unwinnable,
1
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Rezzahan#77802 commented
Your opponent has a Grand Abolisher:
"During your turn, your opponents can't cast spells or activate abilities of artifacts, creatures, or enchantments."