Alliances2

The Cult of the Machine are the natural allies of the Iron Hands — the Adeptus Mechanicus and the disciplined Imperial forces that fight beside the iron: a forge-world's tech-priesthood, a Cadian or Death Korps line regiment, any cold and ordered force that reveres function over flesh and shares the Chapter's contempt for weakness. While the alliance stands, the Mechanicus keeps the Iron Hands' iron running: the ally may repair one friendly walker for free each post-battle phase and furnish augmetic parts as a discount on bionics, and once per campaign phase lends a disciplined fire-support asset — a free off-board heavy attack in one battle. In return the Iron Hands lend their unbreakable line to hold the ally's ground. The pact runs until the forge-alliance is broken or the war moves on.

The melta-and-plasma answer is the one enemy the Iron Hands truly fear — a force built on high-AP anti-armour fire, a melta-heavy raiding force or a plasma gun-line, the matchup that beats the Chapter by bursting the walkers and the Iron Father before the machine cult can compound. It is a standing feud. While it holds, the Iron Hands gain bonus reputation for a decisive win in which they reached the late rounds intact and ground the anti-armour force out — proof that resilience beats burst. But the enemy gains reputation for every battle in which it destroyed a friendly walker or took the Techmarine Out of Action before round four, whatever the result — proof that the iron can be cracked. The feud runs until one side is driven off the contested world.