Worst UR card for an event roaming duelist so far.
Here's why:
1. In order to get even stronger it needs castle of dark illusions (CODI) to be present.
2. It can only "grow" so big.
3. After getting the bonus 100 atk power from CODI, it can get 400 extra power after 4 long grueling turns, and it has to stay on the field to retain this bonus. In total, it can shoot up to 2300 atk.
4. 2300 atk is piss poor compare to many of the level 5 and 6 monsters that are already 2400 and up being summoned and not requiring many turns to power up. Ryu Kokki, a card that can also be gotten from a bonz drop is only an SR, not UR, and has the same attribute and type and is 2400 AND has an extra effect of destroying certain types.
Sh1tty card for a high rarity, does not deserve to be UR. Konami fauked up. Ryu Kokki should've been UR, not this garbage. I understand the pumpking is an iconic card for Bonz but there have been many cards for other even roaming duelists that aren't iconic and are UR. Mai's Vennu Bright Bird of Divinity doesn't even make any sense and is a UR. So goes to show you konami did indeed fauk up.
I'll admit I don't plan on using it in PvP, but it's better than you say. The illusion castle adds 200 attack and the def to zombie monsters, so this cards attack and def ends up being 3000/3200.
3300/3500 maximum, actually. You Summon Pumpking, then flip Castle somehow. Flip increases ATK/DEF by 200, Pumpking increase self by 100 = 2100/2300. Over next 4 standby phases Pumpking gets 1200 more ATK/DEF, to equal earlier total. Beats Blue-Eyes with Mountain. :)
Shhhh. Just because it's bad doesn't mean it can't be fun. Besides, there are counters to do. I'm also not suggesting it's practical, but hey, the hilarity factor would make it worth it... kind of like when you beat CAs with Ghostricks.
Although it's pretty bad on its own it's still playable because of how good the support is. You'd be better off using just about anything else though. My guess is Bonz will have a skill that will make this card actually viable.
Vennu is pretty good and has many tactics (posessed soul, advance draw + mecha phantombeast, e con take, 8 star tributes etc.).
Pumpking on the other hand IS a pretty bad UR but there are many bad URs just because there signature cards like insect queen (only non UR signature card is gate guardian)