The issue with the Titan Shield is indeed a problem, but from what I understand, it only replaces itself in certain scenarios. Obviously that's a bug we want to fix for such a high-profile character, but it's not an easy fix, so it is something we're still working on. The selection of scenarios where it self-replaces is frustrating and can make a match, but it can be worked around, and we're not interested in tuning a character around a bug we plan on fixing.
I've seen some Sentinel Soulless Demons with Strike, and it's an interesting strategy, but again in encourages you as the attacker to get Immunity, buff removal, Accuracy Down, Stun/Freeze, Warriors, not spamming AoE moves, and/or not spamming multi-hit moves, which are all strategies we want to encourage people to utilize for team building. There's many options to deal with him, and bringing just one and making sure he doesn't live a long time usually makes him a trivial bag of HP to work around when he's controlled by the AI.
There is a general issue with Freeze where it falls off in that scenario, for anyone who causes freeze. It is a bug we're intending to fix, but I don't have a timeline.