diff --git a/fftcg/book.py b/fftcg/book.py
index 53b51e0..df41a58 100644
--- a/fftcg/book.py
+++ b/fftcg/book.py
@@ -20,12 +20,12 @@ class Book:
             for card in cards
         ]
         # card back URL
-        urls.append((CARD_BACK_URL, "", ""))
+        urls.insert(0, (CARD_BACK_URL, "", ""))
 
         # multi-threaded download
-        images = ImageLoader.load(urls, num_threads)
+        images = iter(ImageLoader.load(urls, num_threads))
         # card back Image
-        back_image = images.pop(-1)
+        back_image = next(images)
 
         self.__pages = []
 
@@ -63,5 +63,6 @@ class Book:
 
         # save images
         for page in self.__pages:
-            page["file_name"] = os.path.join(IMAGES_DIR_NAME, page["file_name"])
-            page["image"].save(page["file_name"])
+            page["image"].save(
+                os.path.join(IMAGES_DIR_NAME, page["file_name"])
+            )
diff --git a/fftcg/opus.py b/fftcg/opus.py
index 0bb2f64..adb74e0 100644
--- a/fftcg/opus.py
+++ b/fftcg/opus.py
@@ -1,6 +1,6 @@
 import logging
 from dataclasses import replace
-from typing import Callable, Iterator
+from typing import Callable, Iterable
 
 import requests
 import roman
@@ -41,6 +41,8 @@ class Opus(Cards):
             self.__filename = "?"
             params = {"set": "?"}
 
+        logger.info(f"Importing Opus {self.__number}")
+
         # required params:
         #  text
         # supported params:
@@ -82,7 +84,7 @@ class Opus(Cards):
         return self.__number
 
     @property
-    def elemental_decks(self) -> Iterator[TTSDeck]:
+    def elemental_decks(self) -> Iterable[TTSDeck]:
         if self.number in ["PR", "B"]:
             return [TTSDeck(
                 codes=[
diff --git a/fftcg/ttsdeck.py b/fftcg/ttsdeck.py
index 462e818..6998b91 100644
--- a/fftcg/ttsdeck.py
+++ b/fftcg/ttsdeck.py
@@ -72,6 +72,8 @@ class TTSDeck(Cards):
             logger.error("Invalid Deck ID for FFDecks API!")
             return cls([], "", "", True)
 
+        logger.info(f"Importing Deck {deck_id}")
+
         # pre-extract the used data
         deck_cards = [{
             "code": card["card"]["serial_number"],
diff --git a/fftcg/utils.py b/fftcg/utils.py
index 849bc9b..a5faf30 100644
--- a/fftcg/utils.py
+++ b/fftcg/utils.py
@@ -1,4 +1,5 @@
-from typing import Iterator
+import itertools
+from typing import Iterator, Generator, Iterable
 
 from PIL import Image
 
@@ -39,13 +40,17 @@ def encircle_symbol(symbol: str, negative: bool) -> str:
     return chr(ord(base_symbols[1]) + symbol_num)
 
 
-def chunks(chunk_size: int, whole: list) -> Iterator[list]:
-    # while there are elements
-    while whole:
-        # get a chunk
-        yield whole[:chunk_size]
-        # remove that chunk
-        whole = whole[chunk_size:]
+def chunks(chunk_size: int, whole: Iterable) -> Generator[Iterator, None, None]:
+    it = iter(whole)
+    # get chunk
+    while chunk := itertools.islice(it, chunk_size):
+        # stop if no first element was found
+        try:
+            first_el = next(chunk)
+        except StopIteration:
+            return
+        # reattach first element
+        yield itertools.chain((first_el,), chunk)
 
 
 def grid_paste(page: Image.Image, index: int, card: Image.Image) -> None:
diff --git a/fftcgtool.py b/fftcgtool.py
index ae6355c..4ddad76 100755
--- a/fftcgtool.py
+++ b/fftcgtool.py
@@ -12,10 +12,7 @@ OUT_DIR_NAME = "out"  # name of output directory
 
 
 def opus_decks(args: argparse.Namespace) -> list[fftcg.TTSDeck]:
-    # load the current carddb
     carddb = fftcg.CardDB()
-    carddb.load()
-
     decks: list[fftcg.TTSDeck] = []
     for opus_id in args.opus_ids:
         # import an opus
@@ -33,15 +30,11 @@ def opus_decks(args: argparse.Namespace) -> list[fftcg.TTSDeck]:
 
 
 def ffdecks_decks(args: argparse.Namespace) -> list[fftcg.TTSDeck]:
-    # load the current carddb
-    carddb = fftcg.CardDB()
-    carddb.load()
-
     decks: list[fftcg.TTSDeck] = []
     for deck_id in args.deck_ids:
+        # import a deck
         decks.append(fftcg.TTSDeck.from_ffdecks_deck(deck_id))
 
-    # import a deck
     return decks
 
 
@@ -142,6 +135,7 @@ def main() -> None:
     )
 
     logger = logging.getLogger(__name__)
+    logger.info("fftcgtool started.")
     logger.debug(f"{args = }")
 
     # output directory
@@ -150,6 +144,10 @@ def main() -> None:
 
     os.chdir(OUT_DIR_NAME)
 
+    # load the current carddb
+    carddb = fftcg.CardDB()
+    carddb.load()
+
     # call function based on args
     decks = args.func(args)