Mauhúr, Uruk-hai Captain - Intelligence

Mauhúr is strongest when the deck plays cheap Orcs and Goblins, casts him before counter placement, then uses amass, proliferate, and combat pressure to make every +1/+1 counter placement count.

Mauhúr changes how +1/+1 counters are placed. It does not trigger, cannot be copied as a trigger, and one placement of N counters becomes N+1 rather than doubling.

If several eligible Army, Goblin, or Orc creatures each receive +1/+1 counters from separate placements, each placement is increased by one.

Mauhúr is an Orc, so +1/+1 counters placed on him are increased by his own replacement effect.

Any Army qualifies regardless of its other types. Amass creates a 0/0 Army before placing amplified counters when Mauhúr is already applying.

Proliferate is amplified when it places a +1/+1 counter on an eligible Army, Goblin, or Orc. Existing counters are not changed.

If nonlegendary-copy effects allow multiple Mauhúr replacement effects, they can apply cumulatively to the same counter placement.

Curve cheap Orcs into Mauhúr, then use amass and combat counters to grow the board.

Use Goblin density plus counter placement to make several small creatures into threats.

Use Mauhúr as a low-cost counter amplifier for cards that care about modified or enlarged creatures.

Use sacrifice outlets and drain payoffs after counters have already generated combat pressure.