Well, if you just want Kenpachi for League...
Spoiling for a Fight (Passive): Enemy champions of equal or greater level to Kenpachi appear on the minimap when within 2500 units of him, even if in the fog of war. The player using Kenpachi cannot see lower level enemy champions on their minimap. Kenpachi receives a passive movement speed bonus only when moving toward enemy champions of equal or higher level.
Monstrous Strength: Kenpachi swings his sword, creating a shockwave of raw force in an elongated cone. This attack passes through enemies it hits without diminishing in effect. Enemies hit directly are pushed backward the length of the cone, while enemies "clipped" (left or right of center of the effect) are pushed toward the side, similar to Draven's "Stand Aside".
No Need to Hold Back greatly increases the range and positioning effects of Monstrous Strength.
Rise to the Challenge: Kenpachi receives a small damage shield. If this shield is broken (ie, incoming damage from enemy champions equals or exceeds it), Kenpachi receives one stack of 'Joy of Battle' buff. This buff increases his Attack Damage and the amount of damage absorbed by Rise to the Challenge the next time the ability is activated. The duration of the buff is slightly lower than the cooldown of Rise to the Challenge, and the buff can stack with itself.
No Need to Hold Back reduces the cooldown of Rise to the Challenge, and causes Kenpachi to be refunded some of the Energy spent if the shield is broken by damage.
Dreadful Power: (Toggle) Kenpachi's presence is terrifying to his enemies, feeling like a crushing weight baring down on them due to the sheer magnitude of his power. Upon activation, enemies in the area immediately around Kenpachi (starting at melee range) have their attack and movement speed slowed. Every second the toggle remains active, the area of effect and amount of slow increase slightly, with the area growing as a circle centered on Kenpachi.
No Need to Hold Back increases the speed that Dreadful Power's area of effect spreads, and the maximum area of effect that can be achieved.
No Need to Hold Back (Ultimate): Kenpachi gains a percentile bonus to his base Attack Damage and damage reduction equal his current missing health; this bonus is fixed at the time No Need to Hold Back is activated, and will not increase or decrease due to changes in his health after the fact.
No Need to Hold Back does not have a set duration. The effect remains until Kenpachi is killed. The cooldown duration (180 seconds) does not begin until he revives after being killed while the ability is active.