I haven't yet documented what conditions this bug occurs under, but it has occurred on multiple maps under various circumstances and appears quite frequently. When Thunderhoof has greater than 10 ap, if an event triggers (e.g. I attack with another non-thunderhoof champ or a champ dies at the start of my turn), then Thunderhoof's ap will go down to 10 ap (i.e. the ap cap thunderhoof would have with its non-encroached speed of 6) even if Thunderhoof still has 7 spd or 8 spd. The unintentional ap loss is sporadic in it's occurrence but I usually end up triggering it once a game if I've deployed a thunderhoof. The build on my thunderhoof's is unstoppable and charge 3. I can try and elaborate later, just been meaning to post this for the past few weeks. However, I believe this is an interaction with encroached not correctly updated the speed of the champ in the background implementation of the ability.
This reminds me of a problem that the Jakei Elder had with Trail: Snow and Arctic back when it gave SPD. I haven't been able to reproduce this though.
Oh wow, I remember that too now that you mention it. I'll continue trying to figure out a more specific set of conditions under which this interaction occurs.
I've still been encountering this bug fairly often. It has happened under varying situations but it usually occurs when thunderhoof's speed is at least 8 and thunderhoof has stored 12 ap. The specific event that happened today was culler attacked from range on the 3 font Maljaran map (can't remember name) and thunderhoof's ap "magically" dropped from 12 to 10 while the attack procced. Thunderhoof was sitting within the mid font zone and was engaged to 2x undead warriors.
