Brindle Boar

Lifegain stapled to a body, distilled to its most utilitarian form: a 2/2 you cash in for four life on the turn you most need it. Attaching lifegain to a creature is the design pattern that lets a defensive effect masquerade as board presence, and this one does the bare minimum on both axes. The body chump-blocks or trades once, or converts itself into a cushion at the moment of your choosing. The sacrifice clause is the load-bearing part: a creature that simply gained four life on entry would dump the life the turn it arrives, but here you bank the body and pull the trigger later, against a burn spell, a swing you cannot profitably block, or a clock you are racing. The timing answers to no removal spell, since the value is locked into a sacrifice you control rather than a death trigger an opponent can pre-empt. It fires once and then it is gone, and the rate ( for a vanishing 2/2 and four life) was built for the most forgiving environments imaginable, where padding a life total against early aggression is worth a card and a slot. It is the kind of common that fills out a removal-light curve without ever pretending to be more than a speed bump with an exit strategy.