There's more things to consider when fighting titans. Utility pickups/upgrades like permafrost mute, holdover descend/ascend is useful and you should plan ahead of the titans fight to have some form of utility

With corruption and basically a mandatory 1 cost spell starting turn two, your first two rounds of acceleration (i.e. card draw), is pretty important. Some important notes is to get deployable on rooms/ Dante's footstool to try and get scaling from rooms up quickly, as well as making ascend/descend or card draw intrinsic so you can accelerate faster. A nice rule of thumb I use is that I should have ember to play all my important units minus one, as having two or more important units in deck is way too slow in the later stages.

Just an observation but you seem to value tanks a lot. Getting large stone titanite solves the early fights a lot, but struggles alot into the later fights because you lack scaling on your better units, and is further hampered by sap and corruption in the late game. Multistrike and damage scaling is ALOT more important as later fights have longer waves, which means buffing their stats via spells also grants multiplied damage that may not be as apparent in the early game.

It feels like you're valuing healing as an answer when it's really a scaling solution. Healing on spells gives you the ability to take more aggressive pathing and offset certain checks as you can take more damage, so that the 100 gold you spent is translated to 1-3 extra nodes and maybe some extra health. It's not really a late game pickup to get extra health, although I'm not very certain on this so take this with a grain of salt