warmog update ideas for frontline tanks and hp cost champs

warmogs is suppose to be for tanks, which are usually frontline, however with warmogs when combat starts you lose its passive and it just becomes hp, unless you are able to run away.

1st idea I had was too combat against tanks just building thornmail to win versus hp cost tanks "this champion is not effected by grievous wounds till at 35%hp or below"(which is same as when morrellos can inflict it).

my 2nd idea was to save hp for hp cost champions like catalyst because they don't have mana and they are typically the main ones getting this " your hp cost abilities don't cost hp until below 75%".

my 3rd idea was of how to keep its passive viable in combat "upon taking damage continue to restore 25% of your hp over 5 seconds for 5 seconds resets if damage has not been taken within 6 seconds (could even make this a shield) (would like too see minion damage to shut it off removed) ", while this idea is my least favorite I'm am kinda ok with it because if a champ that runs away they are going to heal anyway, but if they don't run it is like they are getting what they were suppose to get from the passive.

for each of these there could be a max hp requirement say like 3000, then 3250, then 3500, or turn these ideas into a new item.

plz vote and leave comments as to why you think any of these idea are bad or maybe even good.