YouTuber DasTactic played in a 4-player Dominions 4 game with 3 other youtubers. It's unusual for a less-experienced player to create good analysis content, but despite being a bit of a multiplayer Dominions newbie, Das' intelligence, curiosity, and teaching ability result in some worthwhile and site-appropriate material.
Using line formation instead of box formation can allow one's squad to envelop an opposing squad faster, which in turn allows for a longer line of contact, meaning more attacks per turn, more enemy losses and morale checks, and a faster enemy rout. Routing squads are not inflicting damage to your troops:
Of course, a longer line of engagement also means one can potentially receive more attacks as well. It's important to get the first strike to reduce the enemy numbers before they get a round of attacks off. Here Das's squad is successfully positioned for a first-strike, being just out of range of the defending cavalry's first turn of movement:
Luckily, the first strike causes the cav to rout immediately before having the chance to put their lances to work. Das wins with no losses:
Das, seeing some unexpectedly large damage numbers in the combat message log, decides to investigate. Dominions 4 combat makes use of exploding 6-sided dice, meaning that a roll of a 6 lets you tack on an additional die. A second six would let you tack on yet another roll. As Das explains, though it's very unlikely, "that's how the game makes it so that a spearman can kill a dragon, technically, if you keep rolling six after six after six."