I'll try
Holgro Part 1
For every 10 hits received, a shield will be applied to the hero which absorbs all incoming damage. The shield lasts for either 5 hits or 10 seconds, then the counter resets.
Holgro Part 2
For every 15 hits dealt, the hero will start dealing double damage. This lasts for 5 hits or 10 seconds, then the counter resets.
Holgro Part 3
For every 5 spells cast, the hero will cast spells without the need for mana. This lasts for 3 spells or 10 seconds, then the counter resets.
Full Holgro
For every 10 hits received, a shield will be applied to the hero which absorbs all incoming damage. The shield lasts for either 5 hits or 10 seconds, then the counter resets.
For every 15 hits dealt, the hero will start dealing double damage. This lasts for 5 hits or 10 seconds, then the counter resets.
For every 5 spells cast, the hero will cast spells without the need for mana. This lasts for 3 spells or 10 seconds, then the counter resets.
If two buffs are active at the same time, the hero will generate an aura that deals damage periodically (every 0.5 second) for 20 seconds.
If all three buffs are active at the same time, the hero becomes invulnerable, deals double damage, and can freely cast spells without the need for mana for 20 seconds.
Extra: Maybe make the hero change colour according the which buffs are activated. The first three parts will turn the hero red, yellow and blue respectively. If the hero for example has both red and blue buffs, the hero turns orange. If the hero has all three buffs, the hero turns black.