Heroes 5.5 WarGame Edition - Tactical Edition.

Nargott, on Hugolek, you mentioned a modified executable... Could you provide more details about what exactly was changed and how?

Three things were changed in the executable itself:
1) The number of slots for classes was increased from 9 to 24 (IDs from 0 to 23).
2) The level thresholds after level 25 were significantly reduced.
3) The number of slots for creatures was increased to 999 (like in NCF).

How it was changed is unknown: the executable itself was taken from an RPE mod.

Added 2 hours 48 minutes ago
I came up with an interesting way to implement the Summoned Phoenix.

For comparison:

Sacred Phoenix (neutral, natural phoenix, does not level up):
Length from tail to beak: 600 cm
Attack = 40
Defense = 40
Damage = 30-30
HP = 60
Speed = 6
Initiative = 15
Large size
Flight
Immunity to fire
Fire Shield
Resurrection
Magic resistance (50%)

Summoned Phoenix (chemical phoenix, steroid phoenix):
Length from tail to beak = 540 + (15/20/25/30 x Magic) cm
Attack = 40
Defense = 40
Damage = 18 + (3/4/5/6 x Magic)
HP = 15/20/25/30 x Magic
Speed = 6
Initiative = 16.2 - (0.3/0.4/0.5/0.6 x Magic)
(Note: initiative cannot be lower than 1)
Large size
Flight
Immunity to fire
Fire Shield
(without resurrection and 50% magic resistance)

The whole idea is that the mage literally levels up the phoenix; the higher the magic skill, the larger the size. And then physics comes into play:
- increased damage (proportional to the cross-section of muscles, or the square of the size)
- increased survivability (proportional to mass, or the cube of the size)
- decreased initiative (proportional to size)

Thus, the larger the phoenix, the more powerful, thicker, and slower it is. Moreover, there is such a thing as an over-pumped (too large) phoenix.

At a length of over 10.5 m (damage 120, HP 510, initiative 6), the phoenix becomes too unwieldy and may start to lose effectiveness. The peak of this form is reached with Magic = 17 and expert summoning.

At a length of 13 m, the phoenix reaches the peak of unwieldiness (damage 170, HP 760, initiative 1). A form close to this is achieved with Magic = 25 on expert, and the exact match is achieved with Magic = 38 with basic summoning (i.e., the phoenix is obtained from a tome).

Seriously, I find the interplay of size and the reduction of the phoenix's initiative to be an interesting mechanic. The fact that the phoenix's effectiveness stops increasing with excessively high magic skill also applies to short-term buffs with a duration of (Magic + 1) / 4. The dependence on magic is strong in both cases, but it stops providing benefits with extremely high stats.