Ironhoof Ox

Forbidding the gang-block is the whole pitch here, and it is a smarter teaching tool than it first appears. Trample asks a newcomer to track damage assignment and do excess-damage arithmetic; menace introduces a counterintuitive double-block requirement. This ability splits the difference, expressing the same combat truth (you cannot wall a determined attacker by stacking bodies in front of it) as a flat prohibition. The defender still has real choices: trade with a single creature large enough to kill it, chump with something smaller and lose the body, or take four to the face. What the clause removes is the safety of arithmetic: the defender cannot gang two small blockers onto the Ox to overwhelm it, so a board full of cheap creatures stops being a wall. No stack interaction, no rules reference required to understand the consequence. The 4/4 frame at five mana matters to the lesson, too: a respectable green beater for its day, large enough that a lone permitted blocker often had to be sizable to survive, so the clause did real work against ground-stall strategies that planned to clog the board. It is clean teaching-set design: one keyword's worth of strategic depth delivered in a single line of plain language, the combat geometry of trample without any of trample's bookkeeping.