I did some maths. Beating Detective Orisolve to the case! Ha!

20$ (2x10) of LP gets you: 3400 LP

25$ of LP gets you: 4375 LP

Toil and Trouble:

20$ gets you:

Rita Alt-art (indeterminate value, highly valued card, possible alt-art tokens)

1 Custom Deck valued at 1350 LP

2150 LP

15 Collection Penta Packs (valued at 2250 LP)

12 Verore Collection Penta Packs (valued at 2400 LP)

12 Sleepers Collection Penta Packs (valued at 2400 LP)

15 Rift Tokens (valued at ~1013 LP)

10 24 Hour 50% IP/XP boosts

40$ of LP (25+10+5) gets you 6160 LP

45$ of LP (25+10+10) gets you 7775 LP

50$ of LP gets you 9375 LP

Monster Mash

40$ Gets you:

Yagron Alt-art (indeterminate value, highly valued card, don't know on tokens)

1 Custom Deck valued at 1350 LP

4680 LP

30 Collection Penta Packs (valued at 4500 LP)

12 Sleeper Penta Packs (valued at 2400 LP)

12 Exiles Penta Packs (valued at 2400 LP)

30 Rift Tokens (valued at 2025 LP)

20 24 Hour 50% IP/XP boosts

So Toil and Trouble needs to outvalue 4375 LP. Does it? It comes with 2150 LP alone, along with almost 7000 LP worth of packs. Even if you don't need any of the cards from the deck, it's a good deal on packs and LP.

Monster Mash needs to beat 9375 LP, and similarly covers about half of it in flat LP. The rest is more than made up for in packs and Rift Tokens. Note that Rift Tokens will stack up very easily if you don't rift run often, meaning that this value may not be used for some time. Likewise, since you don't get to pick your packs it may not be as appealing (particularly to older players) on these lines. However, just looking at it we've got a good deal here.