Haste creature under The Akroan War chapter 2 ability

Question

My opponent plays The Akroan War, then on his next turn the chapter 2 ability triggers.

If I play a creature with haste, does the effect created by the chapter 2 ability apply to that creature? i.e. does that creature have to attack?

Answer 1

Yes

The other answers are good, but to provide the comprehensive rules that explain it:

611.2c If a continuous effect generated by the resolution of a spell or ability modifies the characteristics or changes the controller of any objects, the set of objects it affects is determined when that continuous effect begins. After that point, the set won’t change. (Note that this works differently than a continuous effect from a static ability.) A continuous effect generated by the resolution of a spell or ability that doesn’t modify the characteristics or change the controller of any objects modifies the rules of the game, so it can affect objects that weren’t affected when that continuous effect began. If a single continuous effect has parts that modify the characteristics or changes the controller of any objects and other parts that don’t, the set of objects each part applies to is determined independently.

This particular continuous effect does not modify characteristics or change controllers of objects, so it falls into the second category, and it will effect objects that weren't around at the time it was created. Notably, "must attack if able" is not a characteristic:

109.3. An object’s characteristics are name, mana cost, color, color indicator, card type, subtype, supertype, rules text, abilities, power, toughness, loyalty, defense, hand modifier, and life modifier

Answer 2

Yes

Here is the relevant ruling on gatherer:

If a creature can't attack for any reason (such as being tapped or having come under that player's control that turn), then it doesn't attack. If there's a cost associated with having it attack, the player isn't forced to pay that cost, so it doesn't have to attack in that case either.

So this effect applies at the declare attackers step, not when the second lore counter is removed. This is the same way that Fumiko, Kardur, and angler turtle work.

Answer 3

Yes,

The Akroan War's second chapter ability is worded the same as Kardur, Doomscourge's ETB ability:

When Kardur, Doomscourge enters the battlefield, until your next turn, creatures your opponents control attack each combat if able and attack a player other than you if able.

He has this ruling:

Kardur’s first ability affects all creatures your opponents control, including any that enter the battlefield after the ability resolves.

Answer 4

Yes

I'm not sure why you think it's not clear - it's under your control, and it's able to attack, so it's affected by The Akroan War's 2nd chapter ability and must attack. Haste has no effect except making the creature able to attack; if it didn't have Haste, then it can't attack, so it doesn't have to attack.