1. The Steel Legion Chimera (Reaction: After a non-Vehicle unit you control at this planet is assigned damage by an attack, prevent 1 of that damage.) cannot block area of effect attacks since AOEs are not considered an attack but a card effect of a unit correct? Also there is no limit to how many times a Steel Legion Chimera can activate it's reactions right? ( in otherwords if 5 non-vehicle friendly units on the planet all were straight attacked normally it could use it's reaction to prevent 1 damage for each of these )

2. Can the Rockcrete bunker (If this card has 4 or more damage on it, sacrifice it. Interrupt: When damage is assigned to a unit you control, exhaust this support to reassign 1 of that damage to this support.) block AOE damage? AOE damage is still assigned to a unit so I am thinking yes but am not 100% sure.

3. Stalwart Ogryn (Immune to enemy events) can only block the effects of events but not the costs correct?

4. Rotten Plaguebearers ( Action: Exhaust this unit to deal 1 damage to a target unit at this planet.) from how I understand how actions work, they basically are units that can attack even before ranged units since they have an action window before ranged combat starts right?

1. Correct on both counts.

2. Yes. I believe the only time damage ISN'T assigned is when damage is moved, but I'd have to check to be sure of that.

3. Can only stop the effects of enemy events from applying to itself. Not sure what you mean about costs - you can't normally stop someone paying a cost, but your enemy also can't use your units to pay for his/her own abilities.

4. Correct about timing, but be careful with terminology - they are 'exhausting to deal 1 damage', they are NOT 'attacking'. This is very important as other cards which trigger off things like 'when a unit is attacking' or 'when a unit is damaged by an attack' or similar will NOT apply here.

3. Immunity means 2 things:

a) the Ogryn cannot be targeted by enemy events

b) the Ogryn cannot be affected by enemy events (though other cards will be affected normally)

b means a warpstorm will damage the other units around them, but not the Ogryn.

Re: Plaguebearers

Also worth noting that there's lots of action windows outside of combats too, and you don't even have to be in a combat to use them.

Common uses for Plaguebearers:

1) Use them in the action window in the Command Phase. That way, they've already contributed to command, Zarathur is already present if you've committed him there (for damage boost), and the attack is not only ahead of ranged, its also ahead of Fenrisian Wolf, Archon's Terror, Fetid Haze and other Combat Actions.

2) Use them in the first action window of each combat round after the first. This is a bit like getting a ranged strike every single round, and really really useful.

3) If there's no battle at the planet which they're at, use them in the last action window of the battle phase. This is a good time as its after shields have been used up, doesn't disadvantage you for Tarrus, and they can ready again as soon as the Headquarters Phase happens. This use makes them pretty good command cappers opposite a 1-cost, as theyr'e able to force either shield expenditure, or clear 1HP opposition.

Also worth noting that Plaguebearers are one of the few direct damage effects in Zarathur decks that can hit warlords. In other words, if you have a Zarathur's Flamer to deal with an Honored Librarian plus you have initiative, the best play might be to attack with the Flamers, then sac it to damage the librarian. If they shield successfully, you then smack again with Plaguebearers. If they don't, your Plaguebearers can now damage the Warlord. In contrast, if you were to open with a pink on the Librarian and they don't shield, you might be left with no good target to sacrifice the flamers to, as flamers can't hit warlords.

Similar logic applies with stuff like Tzeentch's Firestorm, which also can't hit Warlords.

There's a reason why Zarathur decks were only considered top tier after Plaguebearers entered the meta: its a seriously strong card.