Merfolk Trickster does not remove "lord" effects
Merfolk Trickster is not removing "lord" effects from other creatures when the lord is targeted by its ETB ability. This has happened to me twice, with two different lords.
Opponent has Kaheera, the Orphanguard and attacks with several 1/1 cat tokens that are 2/2 and have vigilance because of Kaheera's effect. In declare attackers, I cast Merfolk Trickster and target Kaheera. It becomes tapped and loses abilities. But the cat tokens are still 2/2 and I can't make a good block.
Opponent has several rats and Piper of the Swarm, which gives rats menace. In declare attackers, I cast Merfolk Trickster and target piper. It becomes tapped and loses abilities. But the rats still have menace and I can't make the block I want.
I am having the same issue. I was playing a Merfolk Mirror Match with Event ID #231357446.
In Game 1, I attempted to use Merfolk Trickster to tap down one of two Lord of Atlantis my opponent had on the battlefield. What should have happened is that the Merfolk on both sides of the game should have had a -1/-1 to their power and toughness and my opponent's untapped LoA should have lost its Islandwalk. However, as shown in the picture titled Bug Report Game 1, this did not happen.
Furthermore, in game 2, my opponent used Merfolk Trickster on my Master of the Pearl Trident in response to me activating a Mutavault. However when my activated ability resolved my Mutavault still received the +1/+1 and Islandwalk as if MotPT still had its abilities. Please use Bug Report Game 2 as a reference. Per CR 613, adding and removing abilities should be in Layer 6 and subject to time stamps where in both Game 1 and Game 2 examples the abilities should have been removed and changed the nature of combat damage. I request this be investigated and corrected.