A little while back I was going through every 4e book I owned looking for monsters with interesting mechanics and abilities, and as I was doing so, I noticed that there are no monsters that do anything with initiative. None whatsoever. There are a couple that can take actions or turns on multiple initiative counts (like many-headed dragons or extremely fast monsters), but that's as far as 4e goes.
That seemed like a bit of an oversight to me, so I figured I'd have to build one. The flavour text here is for my current game.
Albus is a country partially inspired by what (little) I've read of ancient Japanese culture, so of course there are plenty of samurai. There are three samurai schools in Albus: the School of the Sudden Storm, which teaches speed and ferocity to win a battle in as little time as possible; the School of the Patient Stone, which believes in patience, endurance, and waiting for the right moment to strike; and the School of the Flowing Ice, which advocates observing the flow of battle and manipulating it in one's favour.
The School of the Flowing Ice is the relevant one here. The party met up with and recruited Shizuka, an old white dragonborn samurai and former general of the Albasian army before it was destroyed in the Whitehelm Reaping. Flowing Ice is the least popular of the three schools, and Shizuka is one of the only living masters of the style. His skill with a sword is respectable but not exceptional; it's his ability to read and step around the flow of battle that mark him as a Flowing Ice master.
Mechanically speaking, Shizuka (and any other trained Flowing Ice samurai) has a special ability that lets him spend a minor action to increase his initiative count (he can also reduce it using the normal delay rules). Shizuka gets a damage bonus against creatures with a lower initiative count than his, and a defensive ability against creatures with a higher initiative count.
The combat tactics of this stat block are to pick a target - typically the enemy with the lowest initiative - and to delay so that Shizuka's initiative is just above that of the target. He then gains a damage bonus against that creature, and the ability to reduce the damage of attacks from everything else. Once the target is dealt with, he can then start spending actions to move up the initiative order to pick a new target.
The first time the party saw Shizuka in action was when Kalgar (the dragonborn paladin) challenged him to a duel. The way Kalgar perceived it, Shizuka was performing an odd arrhythmic step technique that confounded the paladin and allowed Shizuka a second consecutive attack. Mechanically Shizuka attacked and stepped up his initiative count above Kalgar's, meaning his turn came before Kalgar's on the next round.
Running this stat block was a lot of fun, but it did have one noticeable drawback, which may be the reason there are no monsters in 4e that mess with initiative. That drawback is bookkeeping. I use a spreadsheet to track initiative, and every time Shizuka bumped up his number, I had to drag around boxes to reflect the new order. I imagine this might be even more annoying with pencil and paper.
But I am willing to sacrifice a little bit of convenience for cool new game mechanics, so I'll probably experiment more with initiative manipulation in the future. Perhaps on monsters or characters themed around time control (chronomancer?). And maybe I'll try a monster with an ability that affects its enemies' initiative, not just its own.
So many possibilities!