Some Vintage and Legacy competitive scenes fully allow players to play with proxies because they understand that the meta evolves in a more meaningful way, or that theres going to be more competition if players can proxy fetch lands, original dual lands, or even power 9 pieces
If you control a flip permanent, you must ensure that it's clear at all times whether the permanent has flipped or not, both when it's untapped and when it's tapped
Trapped within its wordy rules text is a simple idea: you enchant a dead creature from your graveyard, bringing it back to life (with slightly worse hand-eye coordination) to do your bidding
What is MTG Assassins Creed
Vigilance : Until end of turn, other Elves you control gain vigilance and get +1/+1 for each +1/+1 counter on Haldir
removing a problematic creature and even trading off with the residual Salamander token in combat afterwards is a great deal