PSA: Teramoogles are excellent card XP source

Drowning lake is 9 stamina and yields ~11,000 XP. Your top card gets, say, 4x, meaning ~44,000 XP. Your remaining cards just get the straight 11,000 XP.

Stamina value:
Top card: ~4,800 XP per STA
Other cards: ~1,200 XP per STA

Edit: thought about this later:
Total: ~77,000 XP across 4 cards = ~8,500 XP per STA

Edit: u/haledire pointed out that your sub-deck also gets XP.
Total: 121,000 XP across 8 cards = ~13,444 XP per STA

This is actually better than the Teramoogle card.

The only caveat I see - your Teramoogle is 100k XP for future cards, not just ones you have now, allowing you to rush-level-up new cards in the future.

Also, u/Logan_Maransy pointed out that the fact that you can have EXP enhancing coins and fractals on cards, potentially increasing the value above.

u/Hyodra rightly points out that card slots are often at a premium for most players, so it's a tradeoff

Animata: Helm: 8 Stamina node

Seems like +90% drop rate of Teramoogle card

Stamina value:
11,250 XP per STA (factoring in <100% drop rate)

If you want to quickly get newly augmented or acquired cards to max level fast, now is a good time to stock up on Teramoogles.

Then again, I may be post-hoc rationalizing spending 3 hours yesterday farming them.

PS: This community is awesome, and I derive significantly more enjoyment from the game based on what I've learned here over the past month or two. <3