Koth is (99% chance of being) red.
Why are you using Koth's art?
Also the ultimate seems like it will never be used given that the first ability is infinitely better in 99% of situations.
Private Mod Note
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An ability exists on the stack independently of its source. Removal of the source after that time won't affect the ability. Some abilities cause a source to do something rather than the ability. Any activated or triggered ability that references information about the source checks that information when the ability is put onto the stack. Otherwise, it will check that information when it resolves. If the source is no longer in the zone it's expected to be in, its last known information is used.
The "ultimate" is terrible and doesn't feel like it does anything relevant; the loyalty dump is mediocre and seems overcosted, not to mention memory issues. The first ability is the only thing worth it... constant +5/+5 pump is great, but the whole planeswalker is unfocused.
Is there anywhere confirming Koth to be of a certain color? I would have sworn he was sure to be red.
To make a colorless Planeswalker, isn't Karn the obvious choice?
But anyway. The card is honestly a terrible planeswalker. It's most powerful effect is the +2 ability, and it has no ultimate. It's obvious you're just trying to replicate the Kaldra equipment, but that doesn't mean it's not a really crappy planeswalker.