Directly under the preview there was a discussion if Majestic Titan can interact with Holy knight.
Short Version :
You can Force Holy knight to deal its damage to other Units, but Holy Knight can not be chosen to recieve the damage.
Also Seeds of Aggression can deal Damage to Holy Knight.
EDIT : The card does say 'target' which i overread. Can't use Seeds of aggression on an unexhausted Holy Knight.
Why ? Because of the way affecting something is described in the FAQ and the way things were handled up till now, namely that event chains don't matter. (If A causes B and B causes C, the game does not rule that A causes C).
Sources for this are further below.
How does this affect Majestic Titan and Holy Knight ?
1. If the Titan hits the Holy Knight the event for Befuddling Blow does definitely trigger. The Question is if Holy Knight is immune to the effect.
Obviously the 'Befuddling Blow' is used by an opponent in the example, so the only thing that could go wrong is that it does not qualify as 'affecting'.
The relevant part in the FAQ says
[...] A card does not affect another card if an effect chooses it, or if it targets another card with an attack.
Now it is not exactly clear what 'it' references, so we rewrite the statement to make talking about it a little easier.
It either means :
[...] A card A does not affect another card B if an effect chooses A, or if A targets another card with an attack.
[...] A card A does not affect another card B if an effect chooses B, or if B targets another card with an attack.
The first statement is obvious. If such things needed explanation the rule book would need 10x times more text.
(The seconds statement also seems like it could have been written in order to future proof for Seeds of aggression which just ended up not formally causing an attack.)
But now Befuddling Blow does not (formally) affect Holy Knight and the effect has to be evaluated.
2. What if Holy Knight is on the damage receiving side of befuddling blow.
It would be explicitly allowed to chose (but not target) the Holy Knight by the FAQ.
However Befuddling Blow targets the damage receiving Unit so Holy Knight would be affected, hence is immune.
Note that the other case worked because there the Holy Knight was chosen (by the phrase '[...] that Unit [...]') and not targeted.
Edit (all wrong, it does read target) : For Comparions : <wrong>The Card Seed Of Aggression choses both its 'targets'/chosen Units, so Holy Knight can be affected by it. This is where the 'Chain of Events' stuff is relevant.
Yes you use a spell to cause a Unit to deal damage to Holy Knight, but that does not imply that the damage the Unit deals is caused by a spell an Opponent uses (example further below).
Since Holy Knight is not immune to being dealt damage by a Unit, the effect concludes.it**
Conclusion : You can Force Holy knight to deal its damage to other Units, but Holy Knight can not be chosen to receive the damage. Edit : Also Seed of Aggression can not be used on an unexhausted (opposing) Holy Knight.
The FAQ :
A card affects another card or player if it attaches, destroys, removes from the game, targets with an effect, deals damage from an effect, places tokens, removes tokens, moves tokens onto or from another card, cancels it, modifies an ability, or modifies base stats of a unit. A card does not affect another card if an effect chooses it, or if it targets another card with an attack.
Attack with snake --> damage on illusion unit --> trigger illusion ability --> destruction of illusion unit
The scenario with the bat attacking phoenixborn would be like this :
Attack with bat --> activate bat swarm ability --> damage on illusion unit.
Why would illusion trigger in the 2nd case while consume does not trigger in the 1st case ? Both wording contains "as a result of", and if we take your logic on bat case, the destruction of the unit in the 1st case is also due to the attack of the snake (that you control), hence triggering Consume. However, it has been officially ruled that Consume does not trigger in this case. By analogy, it seems legit to say that the illusion ability won't trigger in the 2nd case.
This is the closest we can ever hope to come to logical proof without direct developer ruling.