Gravemaker is also a past HotM with the same odds as Hel.
If you can get Gravemaker, you can often get Hel ( see below).
Gravemaker
Some figures for Gravemaker
click for lots of text
Update Gravemaker
Gravemaker loot box unit pricing is 31,570+ days ( 86.4+ years )
Notes
Click for notes
Loot box unit pricing
5% Appearance Rate in Level 10
So my previous estimated loot box unit pricing for Classic 5* heroes AND 5* HotM was too low.
Hero pool
AND
Devs just made it worse by increasing limited hero pool from 24 to 49.
Wow.
Previous estimate
5* HotM odds
Without transparency I am assuming an odds rate of 1/ 480 for each 5* HotM ( 24 total ).
Current Math
Gravemaker
0.0010204 odds ( = 1/ 980 odds )
4,510+ summons
7 days per summons
FIN
FIN