I am not sure whether the first one would be that busted even for Constructed because of a saga's inherent slowness. If your deck relied only on the third act, it would be a terrible combo. However, I also do not really see a reason to play it in CU/be because the first two acts have such minimal impact.
Investigative Research, however, is a fairly elegant design I could certainly get behind (well, except the name). Clues are a mechanic I would like to see more and in more viable cards at Peasant.
I wanted to cost the first one at 3 since it is mostly a slow Divination, but you do get 2 mana back which you could use to cast the cards. Another version that is less archetype specific was having Act 3 be, "Whenever you cast a spell this turn, draw a card" with the treasure helping you cast the cards and making it more likely you'd draw at least a couple of cards. I'd guess that is even more busted for constructed, even if it is slow.
Here's another quick one.
Inspire the Troops
Cost : 2
I, II: Create an equipment token that has 'Equipped creature gets +1/+1' and 'equip: 1'.
III: Creatures you control gain double strike until end of turn.
I considered making them Bonesplitters instead of Leonin Scimitar's, but that just seems mean. I'm sure you could change the name up and link it to a legend to make it more Saga-ey.
Between Blue getting pushed 2 drop flyers (Skyship Plunderer) and White getting pushed 1 drop flyers (Healer's Hawk and Battlefield Raptor), I'd like to see White get an upgraded option for a 2 drop flyer. Such as a strictly better version of Mistral Charger. That card is still decent but more cards are starting to overtake it.