View Full Version : D&D 5e/Next Bouncy Ball of Kinetic Displacement (PEACH) (5e/any)

Grog Logs
2018-01-27, 10:36 AM
Inspired by the Magical Items of role-playing and amusement (vs. increasing power and combat) in Xanathar's Guide to Everything, I decided to craft one of my own. I would like to see if there any unforeseen ways that this item could break my game.

What would happen if a bouncy ball bounced at exactly the height you dropped it, but it's cumulative kinetic energy was maintained?

Bouncy Balls of Kinetic Displacement
Wonderous item, common

These bouncy balls have been magically enchanted by an advanced Transmutation Wizard seeking a way to entertain his grandchildren. When dropped from a designated height, they will bounce up to their original height a specified number of times regardless of the surface they hit. The number of bounces is equal to what it's cumulative height would have been if the ball was not magically transmuted. See the table below.

Displaced Bounces




Here is a less formatted table showing my work for 50% elasticity. The first column is the number of bounces that the ball in real life (according to basic physics, so in a vacuum, etc). The second column is how high the ball is relative to its starting position for that specific bounce. The third column is the total height that it has bounced over time from the initial drop. Thus, by the third bounce it is only reaching 13% of its original height; but if you add up the height from its 1st bounce (50%), 2nd bounce (25%) and 3rd bounce (13%), you get a cumulative height of 88%. After the ball's 8th bounce, it is bouncing at infinitesimally small heights to effectively have stopped. I'm sure that I could justify this with calculus, if I remembered how to do it.

Bounce / Height (50%) / Cumulative
0 / 100% / N/A
1 / 50% / 50%
2 / 25% / 75%
3 / 13% / 88%
4 / 6% / 94%
5 / 3% / 97%
6 / 2% / 98%
7 / 1% / 99%
8 / 0% / 100%

Thus, in real life a bouncy ball with 50% elasticity would bounce 8 times, with each bounce being smaller and small. Using Excel, I was able to calculate that a ball with 80% elasticity would bounce a total of 30 times for a cumulative of 400% of its original height and a ball with 90% elasticity would bounce a total of 72 times for a cumulative of 900% of its original height.

Question: In what ways could the Party use this item to break the game or make them overpowered in combat?? The Party currently consists of a Gunsmith Artificer, a Transmutation Wizard, two Bards, a Fighter, and a UA Ranger. All are level 2 but I anticipate the campaign going up to at least 11 (if not 20, ***sshhhh***, I can dream). We are playing 5e, but I am also curious how it would effect other editions, in case someone wants to lift my idea for their campaign.

I am familiar with Xykon's Strategy from OOTS #448 (http://www.giantitp.com/forums/showthread.php?43251-Xykon-s-Strategy-Adapted-to-a-Real-D-amp-D-Game-OOTS-448-Spoilers). However, that appears to be either narrative overriding mechanics or something specific to 3.5e. I do not see a way for this plot point to occur in 5e.

The relevant Artificer ability (Infuse Magic) and Wizard ones (Minor Alchemy, Master Transmuter) specify "nonmagical item." In terms of spells, Glyph Ward appears to be able to target magical items; but the time length of 9 bounces (which would be 9 rounds if I was being super lenient), does not seem long enough to make this spell overpowered. The caster could already specify a designated amount of time (e.g., 54 seconds) as part of the trigger without using this magical item. This would render casting the spell on this magical item moot from a mechanics POV. A similar case could be made for Symbol.

Am I missing anything?!? Thank you in advance.