My Problems with Courage of the Colossus

So Strength of the Ages obviously (in my opinion) needed to be replaced- for the reasons that Riot mentioned in the patch notes- but the replacement seems to go directly against a philosphy that Riot cited when removing the Oppressor mastery ( the one that gave +2.5% damage on champions that were CC'd) which was that choosing that mastery wasn't about playstyle, but about whether or not a champion had CC. Courage of the Colossus has even less use than Oppressor if you don't have CC, because at least Oppressor could be useful if your support and/or team had CC to give you that damage bonus even if you yourself did not have CC- CotC's effect only works if you have some form of HARD CC, which narrows down the pool of champions that can use this mastery even further as compared to Oppressor. Thus, even though there is obviously still a choice based on your playstyle, some champions with a playstyle that would benefit from this mastery are locked out of using it.

Mundo, Illaoi, Nasus, Olaf, Yorick, and even champs that do have hard CC, but it takes time to get off, like Tahm Kench, or ones like Shyvana, whose ult has a small knockback, but it can be difficult to hit due to how slowly shyvana flies through the air, and she then has no way to proc her CotC- this mastery is very situational and risky to take in this instance with Shyvana. More champs that this mastery's effectiveness would be greatly reduced on are champions that can only proc this mastery through the use of their ultimate, like Malphite. Until level 6, malphite effectively would not have a keystone mastery, which could be a major problem when you compare it to other masteries, and also when attempting to balance this mastery. If this mastery was balanced to champions that can only use it post-6, then it would theoretically be too strong on champs that can use it pre-6. If this mastery was balanced to the pre-6 champions, then the mastery would be too weak on those who cannot use it pre-6.

All of those champions are tanks that should (in my opinion) be able to use a tank-centric mastery effectively, but are locked out due to their kits, not the playstyle of the person using that champion not being suited to that mastery. This seems like a bigger problem than Oppressor to me as well, because- as a keystone mastery- CotC has more of an effect on the game than Oppressor does, and despite this it is even more exclusive than Oppressor.

Another problem I have with this mastery is that if you are playing a champion who is in love with this mastery (Malphite, Amumu, Alistar) and you get an AMAZING 5-man engage with your AoE hard CC (Malphite ult, Amumu ult, Alistar Q), then your shield is effectively completely useless for the duration that you CC the enemy team. A shield's usefullness is greatly diminished if the enemy is unable to damage you for 1.5 seconds (in the case of Malphite or Alistar) of its 4 second duration. Don't get me wrong, 2.5 seconds is long enough to absorb damage, but it seems like the dream engage is counter-intuitive to getting the full use out of this mastery that is meant to support engage champions. In my opinion, the shield's duration should be increased by the duration of the hard CC, or (if that would be too strong) the shield should come up at the end of the duration of the CC. I know that I may not have the best ideas on how to fix this, I am just throwing ideas out there, I feel this problem needs to be addressed.