What is the best way to go about making sure the tank doesn't die to death sentence or the following melee attack (I play scholar).

Currently I spread my virus and e4e on cd for seperate DSs, but our group hasn't really coordinated a rotation. When the actual death sentence occurs I try to time a adloquium(when is the best time to start casting adlo) or lustrate for as soon as it lands, but sometimes the tank dies even with full hp.

Does Galvanize need to be up on the tank for every incoming death sentence assuming they are at full hp? Should I be using adloquium as my go to spell instead of physick even during downtime to keep shield up as much as possible?Should I be using my stacks on soil or save them all for lustrate?

Any sort of help would be appreciated, thanks.